The more critical folks seem to probbably want it either to lean more heavily into being a stealth game or a platformed proper (rather then it sort of auto-running thing), which would take away the accessibility of the series and probably crater its sales comparitively.
And also I don't think there's every been a game (or book or movie) that was great because it delivered on specifically what critics declared they thought was the right thing. Because great art and entertainment involves surprise and creating new expectations not catering.
Funny thing about it all is that Mirage is exactly what critics declared they want, it is doing this exact thing- hey, you want stealth in a dense urban environment and relatively shorter story? Well here you go!
And despite my reservations of Yahtzee bothering with AC* his main observation that he made about it on a stream recently is correct- Mirage is not "streamlining," as the marketing implies with its "back to the roots" thing, it's just removing things from Valhalla.
Mirage is like FF16- was having some fun with it, then got annoyed, then after I'm done the more I think about it the more pissed off I get. Left a real bad after-taste in my mouth.
I really hope the next game is a fucking 670 hr story campaign with a thousand areas and a million collectibles, just to piss everyone off now and give me a pretty Japanese playground to dick around in while listening to podcasts.
* Yesterday Yahtzee changed his post-ZP stream from streaming the game he reviewed to just streaming what he wants, and it illustrates my point about him- he's just much more fun and interesting when not engaging with the AAA stuff, especially a game like Mirage.