Very well put.
I never wanted Sam to become Captain America. I knew it wouldn't be a winning proposition for him. Like the iceberg that sank the Titanic, it was the mass of ill will, hypocrisy and apathy below the surface that promised to make Sam's journey a short one. Even a blind person could see that Sam wasn't going to be Captain America for very long.
Funny thing about perception. Ours is a country that by and large sees Martin Luther King, Jr. as a great civil rights leader. Very few people see him as an American hero. They just can't connect the dots that in pursuing voting rights and equal protections under the law for everyone that Martin was actually going about the country's business, not just the civil liberties of a minority. There's a lot of that with Sam, too. Readers simply can't or won't embrace him as a great man championing the same ideals as Steve. Ideals that he no doubt formed and held firmly to long before he ever met Steve. There really is only one way to remedy that damning flaw in public perception.
The best that we can hope for with Sam is that he stops playing Robin to Captain America's Batman and becomes Nightwing at some point. The irony is that Sam was meant to be Nightwing all along. The writing regressed him. He fell in line, as you accurately put it.
Accepting the shield and the name just revealed what we all knew: between Sam and Steve there is only one great man, one great mantle. Instead of us focusing on their shared goal -- which, by the way, should be the goal of every citizen who dares call themselves an American -- it became more about Sam stepping out of his inferior position into a higher station. Colossal fail. I don't fault readers for resisting Sam as Captain America. I fault Marvel for not taking this opportunity to build up the Falcon's mantle, separate and distinct from Steve's. What the situation called for was a spin-off, e.g., from Peter Parker Spider-Man to Eddie Brock Venom. But that's not what we got. What we got was a glorified, red, what (?) and blue placeholder ... and Sam was the poorer for it.