We've seen Sam Wilson deal with some pretty difficult issues in the first half of his run. One could never fathom what the murder of both his parents would create within himself, alone. His father murdered tragically while breaking up a street fight, and his mother a community volunteer, murdered in a senseless mugging. It's tragic.
But it's also incredibly difficult, which pushed Sam into a brief life of crime. You would think that would make him give up his run as Captain America. One would be led to believe Sam felt he was unworthy of the shield. Would Steve Rogers resort to a life of crime because the tragedies of life were simply "too difficult"? It would seem to be an impossible task to relive such tragedies and, with everything he's worked so hard for, could Sam Wilson succumb to the grasp of his former criminal lifestyle? We cannot fault Sam for considering the possibility of quitting the role. How else could Sam Wilson be represented as a powerful, black superhero...disassociated from the shield?
The Importance of Representation
Most people of various ethnicities do not want to be represented by whitewashed heroes and villains. They want to see themselves reflected in the characters. Black, Latino and Asian people are a part of history in a way that we don't get to see represented as much. We need our representation to reflect that.
When you have Sam Wilson, already a black superhero, "Falcon", leading the charge as Captain America, it can give the world an idea of what representation of themselves could look like. We have had white Captain Americas in the past, but there's not been a Black Captain America for a long time, or ever. The nation would be outraged if there was not someone in power to speak on behalf of their race. Of course, Sam Wilson is not completely safe from the racism he faces in the real world.
Again...Why Sam Wilson is the Best Thing that ever Happened to Captain America
While Sam Wilson does eventually take up the Captain America mantle after his mentor Steve Rogers, he is not as pure as Steve Rogers in terms of character and legacy. But Sam's heart is as big as Steve's. Steve was aware of whom the Captain America mantle should be passed to, although Sam had to realize this for himself. Once Sam witnessed the shield being represented in a far more unworthy manner, Sam vowed to never give up, and realized he was indeed worthy of the shield...which Steve knew all along. This constant drive will lead Sam Wilson to be a better Captain America than Steve. Sam has the best of both worlds. Captain America's story is all about purpose, in which both Steve and Sam Wilson possess.
Conclusion
Sam Wilson is indeed one of the best things that happened to Captain America, and the Marvel Universe in general...and his name is worthy of the shield.