"You want to cannibalize the most essential character of the show. You say he needs a 'reason'. Well, with a show like AD I'm not so sure this is even true, but let's assume you're right. I think Michael's 'reason' works just as well as any of the other characters', if not ten times better."

This right here is the crux of our disagreement. If you buy into his "I'm doing it for my family" then you won't see that there's a problem. If you don't think he needs a reason and that the inter-familial relationships are strong enough on their own, then you won't see any need for a change. I think both of those issues are problematic and I believe a large number of people who aren't interested in the show also find this to be a shortcoming. Arrested Development is very funny but the name IMO is dead on: none of the characters or relationships are at all developed. Michael often seems like the only person affected by the others' actions. If Gob screws up, Lindsay and the mother rarely care or get upset. Buster's antics are almost always separate issues. As was said earlier, losing Michael would make this show Stella or a sketch show. I agree and that's a major problem, especially when IMO the anchor of the show is barely connected to the others to begin with. The gags in this show are funny but the storylines are not tight at all IMO and that is the achilles heel of the show.

"Yes, Michael's wacky family may mess up his plans at every turn, but those plans are antagonistic in nature. He wants to incite change, and they won't let him. So it's a bit of a role reversal there. At his core, Michael Bluth is a man trying to fix something that is beyond repair, and that never worked all that well to begin with.
"

NewRadio is an example of this premise done better. Dave had to work with everyone to make things work. There was a reason that everyone was involved. He was trying to change the station and make it better but everyone thwarted his ideas. In AD, the business and the family life are fairly separate and consequences are, many times, nil. The importance of the yacht in the family's plans wasn't really made to seem all that important so when Gob sank it, it didn't make much difference. Kitty had access to files but she was never really treated like a big threat.

"Another quasi-Oedipal overtone you have is the George/Michael clash. These two patriachal figures having some bizarre tug of war over the fate of the family business. I think you'd lose a lot of that by casting a female lead."

I think you could easily make Lindsay have similar problems with George and her own daughter.

"Michael is no more the straight-man than the mental ward patient who walks around in a labcoat thinking he's the doctor is a sane man. Sure, he may not be running around thinking he's Peter Pan or Napoleon, but at least those guys are having a good time. Michael burdens himself with some sort of moral code that nobody else lives by, and an illusion of control that he obviously doesn't have. He's the biggest nutcase of them all."

They made this argument on the DVD commentary as well but I think, again, it's part of the problem. Basically you are explaining exactly the issue that I'm trying to fix. Michael is supposed to be the person that you identify with however he is possibly the hardest preson to get a grasp on. There is absolutely no character that anchors the show in reality. Michael is definitely the straight man (most of the jokes are played off of him) but he is not an anchor. If you went with my other suggestion, leaving Michael but making Lindsay the center of the show (and toning her down a bit, making her struggle with her vanity versus her wanting to set things right).