Here's my theory - Vince hates it and feels threatened when anyone appearing in the role of an authority figure, usually garnering heat and a lot of it - Big Johnny/Vickie Guerrero(first run) for example - get too "popular" in the role. I'm sure Vince is trying to protect the Mr.McMahon character and it offends his ego to see someone, especially those he considers less than him (which is everyone), do the job as well as him. If left there for too long, Vince would be forced to admit to himself that it wasn't just him (although Mr.McMahon is great) as much as it is the character.
Another offender of Vince's ego was Jim Ross. I truly believe Vince was threatened by JR's wrestling knowledge, his acumen and most likely, his rapport with the wrestlers. I will bet my left nut that guys were constantly going to JR for advice and this would have burned in Vince's craw. So, he was relieved of his duties.
John Laurinaitis, I believe, has suffered from a little of both these things.
Pefrectly understandable and very good points but I don't think there's anybody i'd go to for advice over Vince...Hate him or love him the man is a wrestling GENIUS.