You're entitled to your opinion (obviously) but I do think you might be jumping the gun just a little bit. If the originals were perfectly written then they wouldn't have had to soft reboot Thor in phase 3. Hawkeye had one character-driven appearance (so to speak) in the first 20 films. Etc.
I think the thing phases 1-3 have over phase 4 is 1) more iconic characters, 2) novelty of crossing over for the first time, and 3) a clearer path of what's coming ahead. There's no question that Captain America means more to more people after 7 films than America Chavez after 15 minutes of non-action screen time. And it means more to see Iron Man meet Spider-Man than it does for Moon Knight to meet Black Knight someday, no question.
But relative to the OG 6, we've barely gotten to know those other characters yet. Someone compiled a screen time list around the time of Shang-Chi:
https://www.reddit.com/r/marvelstudios/comments/q8sdcf/top_characters_by_screen_time/Iron Man still has 3.5x Vision even after Vision had a TV series, for example. Captain Marvel has had less screen time than Sylvie. Etc.
It will take some time but I think a lot of these newbies and 2nd-generation characters can eventually be as beloved as some of the OG6.
And for what it's worth, Thor 4 will in no way be a swan song for Thor.
So at least there's that!