It's just so hard to get excited about starting another multi film connected universe where each film has to set up 2 or more other films rather than simply making a good film on its own merits.
Even if it's well executed, we've still seen it all already so many times that they're basically out of shit
And, tbf no one I knew growing up fucked with F4 so there's no baked in nostalgia love for these characters outside of hardcore comics fans.
If you're excited for Doom, Secret Wars etc. Then I hope they deliver something stellar with this movie that can bring fans back around.
Personally I think the run from Iron Man to Infinty War was bookended by great films with a lot of "serviceable at best" films inbetween, with IW being a particular stand out. But the CU concept of everything tying everything else together is a gimmick, and they should be grateful it was a money printer the first go around.
But it's still a gimmick, with diminishing returns with each new iteration