I think they were really just thrown in the previous games for "fun". GTA IV is headed down a much more serious road. Rockstar plans on making GTA IV fun, but realistic at the same time. No floating, rotating icons, no random jumps that will make everything enter a slow motion mode (even though I do like some of the random jumps, but should be a little less "obvious to be a ramp/jump", like those big platform things at airports, what even are those supposed to be, you know?
I put all my faith with Rockstar, they know what they're doing.