I'm not going to say having the newest or latest and greatest is bad but I also agree if it works why change?
I think the only things you might gain from a new bow is speed, less hand shock, a smoother draw cycle, and weight. Most of the newer bows look a little different with the parallel limb design too. The cool thing about some of the new bows this year is you can find a bow for everything, there are short ATA bows for tree stand hunting, larger ATA bows, speed bows, and there are a few manufactures that are making bows with draw lengths up to 32".
Am I going to buy a new bow this year? Not as of right now, but there are some sweet bows out there.