Nah it’s fair.
The OG avengers cast were the ones who carried those films and Boseman was set to be the leader of the new school
Not really. There were too many unknown variables. They at least left open the possibility of BP still playing a prominent role through his son, but it's not just about BP. It's about Wakanda. And the movie introduced an entire new civilization with Namor's people. Then there's Shang Chi and the 10 Rings organization.
So you have 2 advanced nations in the MCU with super heros, and they are nothing more than a footnote? You have Asgard on earth and it's treated like a 6 flags resort.
Marvel's biggest issue is that it simply has too much going on.
Everything character that dropped in the first 3 phases, you pretty much knew when to expect a sequel and how they generally fit into the Infinity Saga.
The Overall theme of Phase 4 was dealing with the aftermath of the Infinity Saga, but at the same time, it stalled.
At some point, you have to close that chapter totally. If Boseman had lived, he would've still been dealing with Thor, Dr Strange and all of the other content that wasn't well received. That movie would've gotten lost in the mix with everything else. Even to this day, Wakanda Forever is barely mentioned. And it was just as good if not better than the first one.
But I'm gonna keep supporting it.