ces_1 over on WoW Ladies posted bragging about her 9.7k Healing Touch crit, and it reminded me that I do exactly the same thing. For some reason, seeing those big numbers pop up in the middle of battle is an indescribable thrill. Crits are strange entities-- they aren't even always helpful (there are many situations, mostly when aggro is tight, in which big crits are actually bad to get). But big numbers inspire something primal in us. And even if we aren't world-record critting (even in the LJ comments, people are showing off bigger Healing Touch crits), there's something super inspiring about seeing a huge number and then realizing it's your personal best. A 3k Lighting Bolt crit isn't that much, but darned if it wasn't a terrific feeling when I finally hit it on my Shaman.
Loot is fun, but at the highest levels, it's a group thing-- you need to go into somewhere as a group or a raid, and then even if you do down the boss, you have to make sure you win a random roll or however else loot is distributed. But crits are far more personal-- even though they come from that loot, they're a result of all the gear choices you've made and the talents you've chosen for your character. Sure, a big dragon to fly around on is fun, but crits, out of the many rewards we've all earned in Azeroth, are maybe the most personal achievements you can find-- a real, numerical symbol that you've learned how to combine gear, class, and talents to do big things.