I lived in Washington before stops like U Street, Petworth, and others had been built, and the major roads in those neighborhoods were not responsible for the growth they've experienced since the station's openings.
There has been practically no development by the Cheverly station and it also has great road access, and there has also been a lot of devepment in Trinidad and Ivy City even though they have no stations nearby. People are quick to claim that transit stations are responsible for development activity when even a cursory look reveals that the reality is not nearly this simple.