Some of them are short indeed. If you want to use 3-4 buffs at the same time, the first buff close to gone when your done buffing.
But many seem to be just fine for the duration battles last. Makes people consider when to use them a bit more.

I'm a bit more concerned about all thoose lower level tanks, who like to pop ALL their defensive/offensive buffs before actually engaging in combat, then stand there for 10 seconds doing nothing while the buffs just wear of one by one. And THEN he pulls...