Load of horseshyt. This is the worst type of strawman.
All of those characters actually get wins throughout the movie.
And most importantly, they all have valuable skillsets that are traditionally respected in the SW universe.
Finn is *maybe* good with a blaster (And even than, it's Han pulling off no-look killshots
)
Finn can't speak languages, can't fly, can fix shyt, no force powers.
Keep in mind, this doesn't even bring up the fact that most anti-Finns are just as mad about his characterization as they are his skillset. Dude is black comedy relief, period. And that was hidden from the trailers because they knew that it was horrible.
I would have been happy if Finn was a bad ass pilot. Would have been happy if he was a skilled dark side force user. Obviously would have been happy if he was a Mary Sue Skywalker.
Would some of those other characters have had problematic aspects to them if they were black? Maybe. I could see myself feeling a certain way if Boyega got as much screentime as Poe (But to be fair, Oscar Isaac was never marketed like that...his screentime was appropriate for his place on the heigharchy. Ridley/Boyega were ALWAYS the co-leads).
Finally, his character was used as a misdirection plot-device, and none of those other characters were.