You're wrong about one critical thing: Tornadus-T does not SWITCH OUT. Tornadus-T U-TURNS OUT. There is a key difference here. With switching out, you do NOT get to see if your opponent stays in or attempts to pull a double switch on your predicted switch. You DO get to see this when using U-Turn. In addition, U-Turn causes extra damage to whatever check or counter you care to switch in, whereas switching out does not. This removes any element of prediction that the Tornadus-T user would have to do if Torn-T didn't get U-Turn, and instead puts the pressure on the person that's going up against Torn-T to have to predict their opponent's moves. Torn-T isn't all about stats and tangible offensive pressure - it puts mental stress on the opponent as well.
Exactly what I wanted cleared up, and it was.
But that is simply where intelligent playing comes in.
If you bring in your jirachi and you are expecting tornadus to u-turn out (which it will), you can either a) u-turn out yourself, giving you the momentum as the slower poke or b) switch to something like rocky helmet ferrothorn to take advantage of the u-turn.
The power of the switching moves was established during the volt-turn era, but it could (obviously) be stopped.
This proves difficult for tornadus because it has strong offensive capabilities, and regenerator to top it off.
But it still can't be ignored that it is very dependent on rain, it has a weakness to stealth rock that hampers regenerator's potential, and it is not all that strong.
And the question that comes up is whether or not the ability to pivot as tornadus does makes it broken. It neither gives it the ability to sweep not wall a significant portion of the metagame, and does not provide as much support as a slower u-turner as it cannot open up free switches and such. Plus, tornadus cannot u-turn against the faster (or scarved) things that threaten it, which, concerning things like scarf keldeo which can power their way through many things, is quite dangerous.
Tornadus is, in general, a mess of wonderful qualities, but its (few) flaws are still eminent and, in my opinion, place it right alongside the other top-tier ou threats.
And also, on a side note, specially defensive hippowdown handles torn-t very well, and isn't nuetered by the torn+dugtrio combo.
And on another side note, I can guarentee that when the usage statistics come out, the #1 set will be the specs one. It is by far the most common, though whether it is the best is arguable. Thus, it doesn't matter if it can taunt its way through counters and such or u-turn out, because it can't switch moves.
Fyi, Jirachi, landorous, scizor, and hydreigon are all top tier threats that have u-turn, and aren't broken. I seriously doubt giving dragonite or salamence u-turn would make them broken as well.
None of them have 121 base speed, though jirachi can utilize it beautifully in a scarf or spdef set (to counter torn-t even further, nonetheless!) and the sets that utilize u-turn, as mentioned, are choiced, meaning that they don't have the option that lavos was explaining of turning out of a counter after launching a strong (kind of) attack.
Dragonite and mence wouldn't be able to make much use of u-turn because it simply doesn't suit their set up and sweep styles.
They would not want to u-turn out of their +1/+2 speed/attack boosts, it works for torn-t because torn utilizes immediate power rather than setting up