I think the big 330lb, 1-tech, run-stopping specialist is certainly not a high-demand position.
Run-stopping hasn't become less important, it's just that the evolution of the game has changed how teams stop the run.
If you're run-stopping ability makes a team pass more, that's good. It means you're making them one-dimensional. If you can't stop the pass at all, then that's a whole 'nother problem.
I think the Bills would love to force teams to pass and then get after it. They can do that with a high powered offense that puts the opponent in a hole. If they can do it by stopping the run on any given Sunday, then that's icing on the cake.