Rome wasn't built in a day. Tanks have to learn what to do before they can be good, just like everyone else. In addition, there's almost no incentive to leveling to 80 as a tank (or healer), because it is far more efficent 95% of the time to be in a dps style spec when soloing quests and such, trying to work on it before 80 means giving up leveling progress for gear that needs to be replaced almost immediately.
Complaining about handing a tank-to-be 200 level gear in 5 mans and 251 gear from frosts after a lot of grinding is kind of laughable to me, when in reality all it's doing is bypassing a few additional timesinks. The alternative in the past was to just carry people through and/or do gold dkp runs, which have been around a lot longer and fufill the same basic principle, except the 5 man person isn't paying gold for loot or taking up a raid spot.