Seriously, if Tyranitar or Heatran didn't exist until a month before they were to be voted on, people would vote them Uber too.
I'm a bit late to replying to this but, that statement is entirely true >_>.
Mainly, the reason people have been voting Skymin Uber and whatnot don't want to take the chances of experiencing what Garchomp was doing- nearly a year of his bullshit upon the OU metagame. Frankly, people want Skymin in Ubers because they were battling it once and were outlucked. Others only know what Skymin is like on paper, by that, I mean people say "its base 120 Speed and Serene Grace combined with Seed Flare and Air Slash are Uber" or, "It has Earth Power so most of its counters can't switch in safely" or the always funny, "It beats a 6 CM Jirachi with Air Slash flinches and Jirachi wasn't holding Leftovers for some odd reason :(". From those 3 common quotes come the "reasons" that most people feel that Skymin is Uber.
Okay, now, imagine if you were meeting Tyranitar for the first time in your life (in the metagame, of course... unless dinosaurs still exist O_O). Imagine if you saw its movepool and stats for the first time, too. Now, some people will say, "it's way too slow and Fighting attacks can handle it" while others will counter that saying, "But, it gets Dragon Dance and Rock Polish to outspeed most of those Pokemon and can OHKO most of them too. It also has Curse and a Sandstorm Special Defense boost to hide behind, too. This thing is Uber >:[!!!!". Can't the same thing apply to what Skymin does? While some may say, "Ice Shard users can easily OHKO it and let's not forget that Skymin will almost always suffer from the 4 slot syndrome" others will say, "But, it gets Serene Grace, Air Slash, Earth Power a high base Speed, Subtitute, Leech Seed, a high base Special Attack and a psuedo Nasty Plot to use at will"... apparently, Seed Flare is always being used on the switch, will always get the Special Defense drop and has a base PP of 15, then, Air Slash is hitting everything for either neutral or Super Effective will always flinch Skymin's target while it has Earth Power, Substitute, Hidden Power Ice and Leech Seed in the last moveslot, too. Oh and Skymin's always holding a Life Orb, Yache Berry, Wide Lens, King Rock and Leftovers while it's attacking, too.
It seems as if everyone's including every type of way to make Skymin Uber in their reasoning and it's all in one set. Besides, the most common Skymin set is usually a Life Orb set or a Substitute/Leftovers/Attacking set, I honestly don't know where everyone's getting SubSeed from <_<.