Reason #3: Wayne doesn't have a whole lot left to prove as far as music goes.
Think about it: What has Wayne not done when it comes to music? He has hit songs, platinum plaques, and (arguably) a classic album or two. He's got thousands of tracks recorded, more mixtapes than your iPod can handle, and, well, he's done just about everything under the sun (he's even got a freakin' rock album!). So, unless he's just having a ton of fun recording music and wants to continue just for the sake of it, he shouldn't feel bad about stepping back and letting someone else take the baton off his hands. It's been a nice run. But, all runs have to come to an end eventually.