I don't think there's much that's levelled at him on a personal level. I have nothing against him as a man. I don't really see hatred here, mostly deep frustration.
The vast majority of the negativity is aimed at the club's leadership because in 5 years, through a series of terrible decisions, they've taken us from a solid Premier League team who had just won the FA Cup to a club in absolute freefall. We've reached League One now, but who knows where this fall from grace will end?
A good chunk of the perceived reason why this has happened (not the only reason by a long shot) is that we have this insane obsession with playing a style of football that we've never had the players for, is boring to watch and is being tactically undone in the wider game. Yet we persist.
Now we've suffered a double relegation, this is the time for a major reset. Top even did a video last year hinting that things were going to change. McCarron was brought in as the extra help that Rudkin clearly needed, yet here we are appointing a manager that has a footballing philosophy firmly aligned to this failed experiment. Nothing has changed. What's worse is that it's clear we've courted RM for a number of years which means this is an appointment by design, rather than through desperation.
What's worse still is that all the fans have a good grasp of his CV which shows no evidence whatsoever of notable success and, in fact, with the level of recent failure makes the appointment even more questionable.