It seems inevitable. Somebody makes a flick with a superhero, some supporting cast, + 1-2 supervillains. The sequel crams as many IP characters as can conceivably fit in the 120-180-odd minute run time, sensible story be damned.
Ok. I get it. Probably better than most. Economy of scale.
Still, it usually makes for terrible movies unless (like Marvel's Infinity Saga) you created a reason over time for all these supers to be on screen at the same time that doesn't require a ridiculously rushed plot.
What prompts this rant?
A post from the Superman: Legacy table read looked like the collective cast of How The West Was Won. Without a careful build, superhero movies always suffer from character proliferation at the expense of story.