Granted, if your point is that Suicune isn't as common/dominant as Zapdos in GSC nowadays, you are right. Plenty of reasons, all of which follow the recent changes on the metagame:
Teams are more offensive than ever, and these teams just can't afford to have a pokemon that does max 13% to Snorlax after leftovers. Unless you back Cune up with Skarm or Miltank, Curselax (yeah CURSELAX) is gonna wear you down eventually, not to mention drumlax. You might be able to play around Curselax with a Toxic set, but the point of suicune is usually talking with it if you want it able to deal with mixsweepers/egg/marowak, and a surf toxic talk set would just lead to bad talks and won't really work.
On the offensive side, suicune has no offense against any half defensive team, while Zapdos is only really fully walled by Raikou (may take down Snorlax with Thunders especially with spikes down).
Even into stall teams, Zapdos has become more popular than Suicune as the "general defensive coverage + ST" pokemon, while the water-type slot is generally filled with Cloyster/Starmie. While Zapdos acts as a poor-man suicune against most mixsweepers, still does a good job of it (not against ttar though, but Miltank/Starmie/Raikou/Snorlax can generally deal with it depending on the set). The difference lies in the fact that Zapdos does cover many things that Suicune doesn't and that many stall teams have problems with. Vaporeon: A sleep talking cune is a setup bait for vap (unless vap doesn't surf maybe, then you could be able to play around pp if you are lucky). Machamp, especially the Cursetalk kind if Skarm is only your other decent Machamp check. Gengar. Cloyster (a toxic-less Suicune often lets Cloyster switch-in a get its spikes down for free). Heh, and Tenta too. Plus, since the most common kind of "stall" team now is by far heavy defense + spikes, zapdos powers up its offense alongside spikes, which help it wear down the opposing offensive team instead of just "walling one pokemon" like suicune does (and often being set-up bait for another like Suicune is), as suciune generally lets Snorlax switch and set up for free even when you have laid down spikes.
P.S. I forgot to say that Zapdos is immune to Spikes. That's REALLY huge.
And that was myself trying my best to explain why Suicune isn't as common as it was back then. You also have to take into account that back then, when hp legends were banned, suicune saw more usage than zapdos, with the standard stall team often being referred as raikou/snorlax/skarm/miltank/suicune/cloyster or starmie. And Raikou was the better electric, too.
But when you start considering GSC without Suicune is when things become interesting. Suicune is almost the only reason why mixsweepers (those that can) run thunder to begin with (okay vap too?). TTar would be a much more reliable mixsweeper if it hadn't had to worry about Suicune's precense and not being able to 3hko it. Marowak? ST Suicune is arguably the best wak counter, because unlike skarm, cune can actually threaten it. Mixed Snorlax: Unlike zapdos, Suicune always survives three D-Es bar crits. Drumzard was a big threat back then (and still is now). The point is, no matter how uncommon Suicune may be nowadays, Suicune's ability to shut down a big part of the meta has make it one of the most game-defining pokemon through the history of GSC. And Zapdos mattering more than Suicune is a relatively recent shift afterall. Suicune remains as one of the hardest pokemon to break, but obviously, if you compare it to the #2 pokemon in the game you are gonna get a lot of negatives...
As for the movepool, Suicune really has most of what it needs. This is like with Celebi. It doesn't matter if it had gotten Thunder(bolt) or EQ or CC or whatever, you wouldn't have used them on GSC suicune. Sure, Recover would be awesome, but that would've probably moved him to the Uber tier behind the same arguments Celebi was moved up. And only about 5 usable pokemon in OU can learn a 16+ pp recovery move anyway.
Having said all that, a big part of suicune being as uncommon these days, even falling down to around #25, is just that gsc players aren't "good enough". Blissey being #2-3 proves that too.
Teams are more offensive than ever, and these teams just can't afford to have a pokemon that does max 13% to Snorlax after leftovers. Unless you back Cune up with Skarm or Miltank, Curselax (yeah CURSELAX) is gonna wear you down eventually, not to mention drumlax. You might be able to play around Curselax with a Toxic set, but the point of suicune is usually talking with it if you want it able to deal with mixsweepers/egg/marowak, and a surf toxic talk set would just lead to bad talks and won't really work.
On the offensive side, suicune has no offense against any half defensive team, while Zapdos is only really fully walled by Raikou (may take down Snorlax with Thunders especially with spikes down).
Even into stall teams, Zapdos has become more popular than Suicune as the "general defensive coverage + ST" pokemon, while the water-type slot is generally filled with Cloyster/Starmie. While Zapdos acts as a poor-man suicune against most mixsweepers, still does a good job of it (not against ttar though, but Miltank/Starmie/Raikou/Snorlax can generally deal with it depending on the set). The difference lies in the fact that Zapdos does cover many things that Suicune doesn't and that many stall teams have problems with. Vaporeon: A sleep talking cune is a setup bait for vap (unless vap doesn't surf maybe, then you could be able to play around pp if you are lucky). Machamp, especially the Cursetalk kind if Skarm is only your other decent Machamp check. Gengar. Cloyster (a toxic-less Suicune often lets Cloyster switch-in a get its spikes down for free). Heh, and Tenta too. Plus, since the most common kind of "stall" team now is by far heavy defense + spikes, zapdos powers up its offense alongside spikes, which help it wear down the opposing offensive team instead of just "walling one pokemon" like suicune does (and often being set-up bait for another like Suicune is), as suciune generally lets Snorlax switch and set up for free even when you have laid down spikes.
P.S. I forgot to say that Zapdos is immune to Spikes. That's REALLY huge.
And that was myself trying my best to explain why Suicune isn't as common as it was back then. You also have to take into account that back then, when hp legends were banned, suicune saw more usage than zapdos, with the standard stall team often being referred as raikou/snorlax/skarm/miltank/suicune/cloyster or starmie. And Raikou was the better electric, too.
But when you start considering GSC without Suicune is when things become interesting. Suicune is almost the only reason why mixsweepers (those that can) run thunder to begin with (okay vap too?). TTar would be a much more reliable mixsweeper if it hadn't had to worry about Suicune's precense and not being able to 3hko it. Marowak? ST Suicune is arguably the best wak counter, because unlike skarm, cune can actually threaten it. Mixed Snorlax: Unlike zapdos, Suicune always survives three D-Es bar crits. Drumzard was a big threat back then (and still is now). The point is, no matter how uncommon Suicune may be nowadays, Suicune's ability to shut down a big part of the meta has make it one of the most game-defining pokemon through the history of GSC. And Zapdos mattering more than Suicune is a relatively recent shift afterall. Suicune remains as one of the hardest pokemon to break, but obviously, if you compare it to the #2 pokemon in the game you are gonna get a lot of negatives...
As for the movepool, Suicune really has most of what it needs. This is like with Celebi. It doesn't matter if it had gotten Thunder(bolt) or EQ or CC or whatever, you wouldn't have used them on GSC suicune. Sure, Recover would be awesome, but that would've probably moved him to the Uber tier behind the same arguments Celebi was moved up. And only about 5 usable pokemon in OU can learn a 16+ pp recovery move anyway.
Having said all that, a big part of suicune being as uncommon these days, even falling down to around #25, is just that gsc players aren't "good enough". Blissey being #2-3 proves that too.