Why you lower your raises when the blinds get higher.

[SuperUberBob]

I lower them because a lesser raise will have the same effect as a larger raise. In other words, all the hands that would fold to a 3x BB raise would do so to a 2.5x BB raise as well. If you can invest 1 less SB into stealing a pot preflop and still have the same result, then the risk/reward ratio tilts more in your favor.