Why X-Men: Dark Phoenix Failed
4. It Is WAY Too Serious
X-Men: Apocalypse has a lot to answer for when it comes to the tonal mistakes of Dark Phoenix. That more camp, sillier film tanked critically and was widely called the worst ever X-Men movie (harsh words, but it's not hard to find them repeatedly used online) with particular focus on the more outrageous elements and the slightly strange tone. It was too camp, too zany and Oscar Isaac's titular villain was too pantomimey by half.
Naturally, because the response to any "failure" pin-pointed to those sorts of issues is for people involved to promise that the next time things will be darker or grittier, that's what happened here. Interviews appeared with those promises and Fox absolutely sought to make a darker film.
The problem with that is they released it when you don't release dark films. Say what you want about the shifting release patterns of recent years, but summer blockbusters are not dark and complex and even if Dark Phoenix fails to be as complex as it wanted, it aspires to be both of those compared to Apocalypse.
Releasing it in February as planned would have matched its tone far better, because it's fundamentally an on-season blockbuster. Unfortunately, Fox Studios CEO Stacey Snider insisted on the change to give Alita: Battle Angel more space and screwing Dark Phoenix not only on the tonal disparity but also by putting it out after Captain Marvel and Endgame both scored major victories for Marvel. It was in a graveyard before it was even alive.