What about what the Puerto Rican people actually want?
What about what the people of the United States want? Its our country, we should be the final say on whether or not the US admits a new state
Pretty sure the vast majority of Americans wouldn't mind if Puerto Rico became a state or not. And plus, it's not directly their say. It's Congress's say. If people of the United States don't agree, they can vote the representatives who admitted Puerto Rico out.
Also, there wasn't any problem with Hawaii and Alaska becoming states, so I doubt there would be any fuss with Puerto Rico, even with the whole "Puerto Rico speaks Spanish more than English" thing.