I agree with y'all. One of my original worries when Solace began the GBU Pokedex project was that folks who identified largely with the VGC2011 metagame would try to apply the exact same principles to the GBU Double Battle metagame, or basically use the exact same threats and numbers except replace Gen V Pokemon for Gen I - Gen V Pokemon. Obviously I came to see that that wasn't the case, that the people writing the analyses for Double Battles were clearly well-versed in the GBU metagame(s), but before that, when I was still uncertain, one of my worries within the concern was that people would imagine Tailwind to be a much bigger deal than it really is.
That's not to say Tailwind is "bad," only, while (and this is just as far as I've seen) Tailwind and Trick Room were viewed as relative equals in the VGC, it's very different in the GBU. Tailwind enjoys a few advantages over Trick Room, like (up to) +1 speed priority versus a much lower number, but that doesn't take away some of the chief advantages of Trick Room. One of these is that Trick Room Pokemon don't need any EV investment in Spe unless they're trying to outrun another TR-usable Pokemon outside of the TR environment. They get to put that into their defenses; plus, if two Pokemon have about the same BST, and one has great Spe and the other abysmal Spe, the latter is going to get to have those numbers in another stat, AND be "faster" than the former in TR. Another is the so-called "immunity" to effects like Icy Wind and Thunder Wave, which, while still hindering the TR Pokemon through damage or full paralysis, actually make the Pokemon faster rather than slower. The most important factor in favor of TR, I think, is that it lasts one more turn than Tailwind. This is not just because it gives one more turn of favorable conditions to the TR team, but, since double Protecting nullifies 2/3 of the Tailwind-Pokemon's turns of damage and only 1/2 of the TR Pokemon's, and since against skillful players Protect is so common, one can almost think of Trick Room as getting twice as many turns of unmitigated damage.
Weather teams are an entirely different story, and can win out in turn one just by fast Fake Outs (Ludicolo, for instance, outspeeding any other Fake Outer in rain, which puts you at an advantage unless the foe also chose, say, Tornadus + Ludicolo, predicting your rain team; but this is pretty unlikely) and by the sheer power of rain- or sun-boosted moves, to give a couple examples. One of the fun things about a rain team versus a Tailwind team is that the foe never seems to know that Ludicolo has the faster Fake Out than, say, Mienshao in the rain. Ludicolo Fake Out Tornadus, Mienshao Fake Outs Ludicolo uselessly, and I write a little mark to indicate the foe D/C'd before it even happens, because it's that predictable at that point.
Another factor in Tailwind that comes to mind (which isn't really a reason against it, only something I've noticed) is that you'll find that your goodstuff, medium-Spe Pokemon outspeed the foes even outside of Tailwind 80% of the battles. As far as I've seen, only fairly dedicated players use Choice Scarfs, partially because of the difficulty of obtaining one this generation and partially because it's an unattractive option for players who haven't tailored their Pokemon for specific party roles. Scarfs are one of the big things that do Tailwind parties in. Of course, you can have Pokemon that are fast enough to outspeed any Scarfer when Tailwind is up on your side, but then you lose out on attack power unless you're using goodstuffs Pokemon like Latios. Trick Room, on the other hand, doesn't suffer as much with having to hit certain marks; rather, TR-usable Pokemon are sort of "rewarded" for losing Spe by getting that number often replenished in another stat.
With the existence of the HG/SS tutors, Tailwind gains some viability in disguising itself within uncommon Pokemon, but those Pokemon are very often Flying-types (with the occasional Levitator or Water-type) and if they rose to any level of popularity, they would probably become easy enough to spot that one of your two-man vanguard could KO one of them right off the bat. There aren't very many bulky, non-Uber users of the move. Whereas Trick Room is swimming with them (though with also a sizeable weakness to a few different types), many of which are often able to take a supereffective hit and still set up TR, if your Tailwind Pokemon doesn't have Priority or is named Suicune or Latias, you will encounter situations where the move doesn't go off as planned.
I would like to see what people can do with Tailwind, but I don't see it taking over the metagame. There are just too many powerhouses duking it out already for Tailwind to get an edge in. I remember thinking it was neat way back when, and not pursuing it in spite of that interest, and now I'm not eager to try it out again; it's at the back of my list of teams-to-build. I'd be honored if y'all would post Tailwind teams you've used, whether or not successfully. Actually, you can post any sort of team you've used anytime you want, only Tailwind is on my mind at the moment.
I'll write some more later, I need to prepare for class. If you guys want to make these posts collections of your thoughts on the metagame in general, I can add them to the OP (And if you think you already made a post that deserves a hyperlink, feel free to point it out to me).