I get your concept, but I feel like this kind of ignores that he was stepping into the role of Captain America. Where there are already set expectations that limit what you can do to make it work. And what they could've done to make it work is antithetical to what the studio head, writer, and lead actor wanted. Sam came out of the MCU oven a one note sidekick, and he's never changed.
Beyond that, I'm talking mostly about potential box office success. I'm not aware of how well Sam sold in the comics, but I'm going to guess he wasn't the highest selling Captain America.
The obvious answer was always to go with Bucky. I'm happy they didn't, so he didn't get caught in that vortex, but both the character and actor are far more dynamic.