Given his "success", if he was that admired and respected across the league, he would have been in on his first ballot. He just isn't. He is paying the price for his arrogance.
NE has always had very good player development types who are now scattered around the league as successful GMs. Belichick never really acknowledged their contribution to "his" -- really NE's overall success -- and lots of these folks resent it. You add the incessant cheating by NE and you have what I will call the "Ron Santo" effect. A guy who, by the numbers, should have been in the HOF but only got there after his death because he treated lots of people like shit.
The fact that no one wants him as their head coach even in the current dearth of good candidates further demonstrates that he isn't respected in NFL circles.