Well that's just it ... they shouldn't have tried this current era stuff because most of it falls short. Setting the established MCU aside as background and focusing on a really great FF movie may have been the better move to usher in a new era.
IMHO, it's just a very complex situation, a function of logistics and desperation. The MCU has been running so long that they have almost run out of actors to star in their films. They have cast so many people now, that it limits their options. The other thing is when you have the entire franchise struggling, you need a really bankable actor to lead the film and draw in audiences. How many people can do that? (Tom Hanks, Denzel Washington, Keanu Reeves, Tom Cruise, Leonardo DiCaprio, Daniel Day Lewis, it's a super short list) And out of those guys, who is going to sign a 6-7 picture long term contract to play the same character? The last time the very casual movie going audience seemed to be excited to go see some films was Barbie and Oppenheimer. But is it worth it to go now? Gas, time, parking, 45 minutes of previews/trailers, people with their cell phones and babies in theaters, etc, etc.
As the release date is 26/27, that means they are creating distance. Because there is no guarantee we won't face another long term pandemic lockdown. Or that, at least in the US, there won't be looting/rioting/burning/total destruction in major cities for at least a year ( It happened in 2020) If that happens, the basic local movie theater is going to die off. I mean look at the gym/fitness industry, the lockdowns and riots killed off so many of them, they couldn't survive.
I personally don't think it's good casting, but it was the best they could do in a desperate situation. Their releases, most of them lately, have really suffered and angered fans. Though, if you look at it from a writing perspective, it could get ugly. RDJ can only play RDJ. So to make him a 'bad guy', the most efficient way to do that if for him to kill a crap load of Avengers. To set a different tone. Shang Chi, Shuri, The Eternals, Pepper Potts, etc, etc, there's a long list of characters that aren't helping the MCU right now and could get massacred in the films.
The loss of Emily Blunt as Sue Storm had a huge domino effect here IMHO. She's a great performer and she can consistently elevate the material. She can do physical roles and she appeals aesthetically to both men and women. But since she hasn't won an Oscar yet, there was close to no chance she'd sign a long term 7 picture deal. Also John Krasinki is a package deal with Blunt, and people hate working with that guy. I don't think the functional parts of the MCU could survive Krasinksi's ego for six films and a decade of bloat. Had Blunt got cast as Sue Storm in F4, maybe this RDJ stunt casting wouldn't have happened. Feige might have more confidence in a less brand name actor for Doom. My current pick would have been Kevin Spacey. Strange as that might sound. ( Though I think the best choice, Mads Mikkelson, was already wasted in Dr Strange 1) Phenomenal actor, whatever people think of his off camera scandals, the guy can bring it. And just enough tension in the casting to get people casually interested in seeing how it would turn out. Also he'd might be more apt to sign a long term deal and sign for cheaper given his situation. He's already baked in as a 'bad guy' by perception already, why not maximize that. But that's just me.
Paul W.S Anderson's Alien Vs Predator was kind of a mediocre film ( But looked really good for the practical budget and had some nice fight scenes). But good God, the toys and merchandise from it was incredible. The Predator designs were really awesome. Even a mediocre film can give you good toys. I think that's my biggest problem as a collector with some MCUreleases. For example, I though Shang Chi was a mediocre film, but also the merchandise and figures, IMHO, really sucked too. As collectors, I feel we at least have the back end hope of good figures as a consolation prize whereas most casual movie goers don't have that option.
I predict a lot of cameos, thus a lot of figures. Tons and tons of figures. Maybe that's a good thing for all of us here. I didn't love Ultron, but that Hulkbuster was, merchandise wise, a literal money printing press all it's own. I can live with cool toys as the only consolation prize here.