In all seriousness, I think my major concern with Windu being alive (or most of the dead prequel and OT characters) is the same issue I had with the "fishbowl" nature of the PT.
The galaxy as portrayed in the original films is a vast, vast galaxy of which we're only seeing an extremely small part. Characters like Luke, Leia, and Vader are connected because they fall into the tropes of heroes being connected with villains. Whether it's a fairy tale where the bad person killed the good person's parents, or the good child was actually the secret heir to the throne who was stolen away or whathaveyou, there are long-established tropes of secret power/regnal legitimacy/etc. and we accept that because Star Wars is basically space fantasy.
In the PT, though, everyone's just connected as some form of elaborate call-back. Anakin built C-3PO. Chewie fought with Yoda. Palpatine may be Anakin's sorta-kinda-father through the Force. This makes the galaxy seem a lot smaller than it should be. It's not enough that 3PO enters the story in a similar way to R2 (e.g., as an otherwise anonymous protocol droid serving the Nabooian royal court or whatever). Anakin had to build him. It's not enough that droids (as evidenced by 3PO) seem to have some odd pseudo-religious notion of "the Maker." No, no, 3PO literally means Anakin. It's not enough that Chewie just happened to fight in the Clone Wars. No, he has to have been one of the generals alongside Yoda himself. It's like the deleted sequence from TPM where a young Greedo gets into a fight with Anakin in the street and is told he's gonna come to a bad end some day. I mean, seriously, these are just call backs for the sake of call backs, and they hurt the story.
Resurrecting Fett is...dubious. Understandable, but dubious. Similar story with Darth Maul. I haven't gotten that far in the Clone Wars cartoon, but man...that's...gonna be a heavy lift for me. The guy who was BISECTED AND FELL DOWN A BOTTOMLESS SHAFT OF ENERGY coming back does not make a lick of sense to me.
For Mace Windu to come back, it would just be too unbelievable. I don't care if he has the power of the Force. He had his freaking arms chopped off, he was shot with lightning, and blasted out a window at the TOP of a planet that is a giant city, then fell down until he disappeared out of sight. The only thing missing was a muffled >thud< and a dust cloud a la Wile E. Coyote.
Connecting everything to everything and continually recycling old characters is, to me, a sign of truly amateurish writing. I expect it from low-grade fan fiction. I expect a lot better from people who get paid to write.