In general, I am not a fan of having several classes of vesssel that are just scaled versions of each other. The Klingon bird of prey, for example, ticks me off.
But in this case I think it might be practical. I mean, the TOS BOP has exceptionally simple topography: an extruded saucer with wings. And from the point of view of secrecy, if all your ships look alike then an enemy agent can't be sure she saw a Corvette or a Dreadnaught without scanners that would give her presence away.
I'm not sure how much I buy the idea, but I'm not opposed to it... Which is odd.