Well, you have both ladder and leaderboard representation there. Sure, Holy Paladin is most prevalent in 3v3 (and therefore even more so in tournaments, since that's where people do all min-maxing), but Holy Priests are pretty frequent at 2400+ and dominate 2v2. Saying that priests and druids are bad right now and you have to forget about gladiator is ridiculous. Right now, paladins are slightly overtuned, mistweavers don't exist, and everything else is good (when it comes to healing).
The problem with getting your data from tournaments is that if one spec is 1% better than the other, you'll see most people picking the better spec. And even in overall WoW population, you'll see a significant bias towards whatever is strong and against whatever is weak. I'm pretty sure most 2.4k+ players can get at the very least 2.2k (and probably close to 2.4k anyway) with whatever is currently the absolutely worst spec in the game except tanks (since they have no reasonable win condition). But there's no point, since you're not getting any additional rewards for your additional effort. You'd certainly see a huge influx of high rated Fury Warriors, Outlaw Rogues, etc., if they added spec-specific R1 titles.