Gloves of Spell Mastery, for instance, a high level tailoring item that used to say "+2% chance to crit" before the expansion now says a critical strike rating increase of 28. That still gives a +2% chance to crit at 60, but if you've made it to 66, it only gives a +1.5% chance to crit, and at 70, that drops to +1.26%. They're the same gloves, but the crit bonus you gain from them has dropped in almost half.
As an aside, don't forget that RatingBuster, an addon Eliah looked at last week, can help you out with all of this-- it'll let you know exactly what those ratings mean for the level you're at. You can literally watch your numbers drop after you ding!
Of course, as Relmstein points out, this isn't really anything to get worked up about, because the equipment is scaling with the rating, and so by 70, you'll hopefully be finding gloves with an even higher critical strike rating. And this does have, as he notes, the added benefit that 57s-60s (like my rogue right now) will get a little buff from having overpowered gear for their level, since the Gloves, for example, will actually give more than a 2% crit when worn by someone below 60. But it's true that on the way up, classes like Warriors and Rogues that depend so much on hits and crits will suffer a little bit.