It's far more this, plus a combo of not only targeting the largest common denominator, but having to do that internationally which obliterates any script's ability to tie into cultural knowledge or norms, or the "vibes" of any given population. Not to mention nothing ever goes to screen that can't be quickly scooped out to appease the Chinese censors, lest they lose the largest audience on earth right out of the gate.

And I don't think you can totally disregard that movies cost more than they ever have to make while also looking worse than they ever have. The special effects in Pirates of the Caribbean utterly trounce newer productions that cost far more to make just for everyone to bounce around green screen stages in motion capture pajamas, and to be clear, this is not industry professionals costing too much or being bad at their jobs, it's almost solely down to the studios wanting the ability to hysterically tinker with films until the 11th hour to ensure maximum market reach.

The industry should be ashamed of itself.