You mis-understood me. The OT cast in DOFP were not a burden. Quite the opposite in fact. The problem was that people liked them, were happy to see them return, and would therefore be disappointed when they didn't again. First Class could have had a nice little run with the cast it assembled, but most of them were jettisoned for DOFP.
Apocalypse was technically a 3rd part, but in many ways it was another reboot as it had to introduce a new cast and once again distance itself from the originals.
With Apocalypse, we have now a solid trilogy of quasi-reboots/set up in the same franchise (X1, FC and Apocalypse). That's too much I think, but understandable considering the circumstances. Only FC manages to be both a reboot/set up of the new team AND tell a complete story in its own right, both X1 and Apocalypse are obviously just introductions with no real pay off.
This is why I'm very puzzled why people are calling for a reboot yet AGAIN. When are we ever going to delve into the psychology of characters not named Wolverine (and ever since FC and DOFP did wonders with them, Xavier, Magneto and Mystique) and expand on them? We are left in a position where we can just jump straight in and explore the new characters by the next movie (and these new characters do not have the baggage of the previous trilogies), why throw that away?
I agree for the most part. A vast majority of things that bug me will be shrugged off or not even noticed by a lot of people.
Alternatively, we're getting to a stage where the franchise is so convoluted and self-referencing that you need to know a fair bit to appreciate it. So you're either so casual you're missing out, or you're so invested that you're getting annoyed.
The questions I was asked most by random people were "is this in the past again?", "are they time travelling again?" and of course "is Wolverine in it?". Maybe it's anecdotal, but I get the feeling that the GA are going to start needing a map to plot this franchise out. I fear the broad strokes fans are going to become more and more confused when major differences start cropping up because they don't fully appreciate the effects of the DOFP clean slate.
And this is I think why the box office for this franchise seems to be reaching its ceiling. With the MCU, they pump out origin stories every few years with a brand new character as a way to introduce new viewers to their world. The X-Men does not have the luxury of having so many movies with brand new characters (yet). It is in effect one giant story that spans decades and two different timelines. It has actually become the most niche and geeky of the comic book franchises. XD
While I do agree with you, I don't think things are as dire because Apocalypse' greatest sin was that its an origin movie and a rehash yet again, so depending on how things are pulled off the next trilogy can dissociate itself from the previous movies (as long it does not start crashing into the 2000s and recasting major characters who are supposed to be the same age as in the OT, i.e. a recast for Rogue in the 2000s).
And in my experience the casual fans seem the most happiest with the franchise regardless of plot holes, provided the movie is entertaining enough (hell The Wolverine is the most self-contained and least problematic continuity-wise story of the bunch but is dismissed by a lot of my friends as the worst because it's slow and boring; alternatively TLS and Origins:Wolverine despite all its faults seem to be perceived positively by my friends simply because they are not boring).
It's hard to determine how a truly fresh viewer would perceive Apocalypse though considering the people I've watched with have a basic knowledge of the X-Men status quo (Jean is the most powerful X-Man, Xavier and Magneto are frenemies, Mystique used to be evil but now she's good). It would be interesting to let Apocalypse be the first X-Men movie somebody has ever watched and see whether they understand what's going on.