yes totally about perspective. most people don't lean on the run for their offense for starters. the benefits of a fb for them don't touch the benefit of another spot to grow a guy or hit a play %. for those who do rely on the run, you have to decide do i want another spot to grow a guy or do i want consistency? in a vacuum a yard or two here and there doesn't sound like much, but the plays don't unfold in a vacuum. a yard or two can mean a completely different play call for the next play. it can mean field position. it can mean points or no points. a good fb gives you consistency there which gives you more control. thats the main benefit of running is more control and predictability from play to play. its as much about the play that gets called, as it is what the result of that play will cause to be called next.
i wouldn't advocate fighting for one if he will only ever be a fb, but i don't hate going 1-2k miles to knock sims off if i have to. its pretty common that good rbs have at least decent fb cores too which can kill two birds with one stone.