I understand what you're saying, but I think your last line expresses the best sentiment. It's a great first step, with the emphasis on first. The NFL clearly has a long way still to go, but if Michael Sam shows what he's capable of doing with the Rams, then that paves the way for others in the future and for Michael Sam to advance by possibly being traded to another higher-rated team.
People are generally scared of change. Few people like being the first with something, and that's reflected in what's happened here. The good...no, great...news is that the next time will no longer be the first. Each time, each step, makes it easier for the next time.
Good luck and best wishes for the Rams, and I hope the rest of the teams get to see what they missed because they were afraid....