If you're going to take your examples and go for more depth, just prove my point.
I do not know all the mentioned actors, but they are unique characters, or new characters (little known) to most of the audience. but using one of their examples, do you think T.holland is dearer than Tobey? or did ben afleck win the audience after the C.bale? or maybe the next actor to do wolverine will get the public's empathy quickly?
and you forgot to mention the situation of some of the franchises that these actors have assumed, such as the case of the C.baile that took a franchise 8 years after a film with 10% approval, and the H.ledger, did a great job, but that character was more than 11 years without appearing in some movie,but it is not a subject for this topic.
But coming back to talk about the cast of x-men
Of course, they do not have the same impact as the old cast, this is natural and would occur in any known franchise, be it x-men, avengers and etc, when you have an original/actor cast loved by the public and with good films over the years, and this cast is changed, and of course there will be resistance from the audience with the new cast,I, you, fox, marvel, WB, everyone knows that.
McAvoy is praised, Fassbender too, many critics praised the cast's choices, the issue and that they simply were not luck enough to debut in a good movie(sophie, tye, shipp, olivia and etc) . It's no excuse is a logical thing.