I think about that a bit too JvK but the Mr. McMahon character is so ingrained in people's minds now it would be weird to see him in the booth again. Honestly if Shane ever comes back I think he'd be great as lead announcer. I remember when he did it for awhile on their MTV show with Jim Cornette and he came off pretty well.
As to the question, I don't think it's always been perfect. Their best people were Vince, Bobby, Jesse and Monsoon. I've often spoke about my dissatisfaction with Lawler as Heenan's replacement, and I really didn't begin to appreciate him until Paul Heyman replaced him who I hated in the booth then.
This was probably one of my favorite moments of Raw ever.
http://youtu.be/VsF2l8c5Os8?list=LLEJaY88iIto9lXe23XnHPuw