1) The general feeling that they haven't really had to work for their "success", so it's kind of hard to admire or be impressed by anything they do.
2) I guess a lot of rival fans resent the knock-on effect that these clubs have on the rest of us in terms of the prices and wages we're forced to pay.
3) It's really fucking hard to gain any traction on team building, player development and generally trying to do things in a different / smarter way when fuckers like City, Chelsea and PSG are constantly hovering around, unsettling and poaching all of your best players. (I do think the other clubs are starting to turn this back on them now, and are quite deliberately milking these clubs for as much of their money as they can get, which is great in the long-term, but it's probably also a tacit admission that you're unlikely to be compete in the short-term.)
4) Personally speaking, I just feel like all of the skill goes out of the coaching side of the game when teams are run like that. Part of what makes following a club interesting is things like how you manage a limited squad across a season and how you shuffle the pack when you're running low on options. It's things like the game plans and tactics you have to come up with to beat a tougher opponent, and seeing players who have been with you for years develop and find another level. It just doesn't feel like there's much skill or craft involved when you never have to worry about things like squad depth or fatigue. I just find it really boring.