Leveling makes you “weaker” in Cataclysm
Your primary stats go up, but your combat ratings go down. The reason for this is that those ratings convert to percentages. If you started with say 50% crit chance, and then gained a level and your new gear had say +4% crit chance instead of +2% crit chance, then you’d quickly get to 100% crit and stay there. This was the reason we implemented combat ratings in the first place. (You can blame Blackhand’s Breadth.)
This particularly gets to be a problem when you reach max level. The reason is because you are going to go through several tiers of gear without increasing your character level, so we need to have enough space in the numbers for them to increase. We figure out what the highest say crit and haste chance the game can handle and then work backwards giving each tier a meaningful upgrade (or getting new gear won’t be fun) and that determines the combat ratings on the starting gear.
We definitely understand the confusion / weird perception issues this causes and we’ve talked about some ways to completely revamp the game’s combat equations so that we didn’t need to use percentage-based stats influenced by ratings with diminishing returns. That is too large a change for Cataclysm, but something we might do in the future (when we aren’t also tackling talent and glyph revamps).
Also remember that if you are leveling to 85, you are skipping over a lot of potential quest rewards that you can’t get yet. The item leaps among levels are pretty large at level 80-85, which we had to do to make the upgrades feel meaningful. (Imagine the alternatives where you could go to Twilight Highlands directly from Icecrown and do okay.) Once those quest items are in, you’ll be more powerful as you level.