Sometimes it's the same, and sometimes the returned value is wider. independent_bits_engine can be used as an adaptor to go from any given width to any other width.

The goal of the proposal isn't to make people use linear_congruential_engine with 8-bit numbers or something. The goal is to make people use 8-bit distributions using existing engines. I suppose allowing the instantiation of engines with 8-bit types is a drive-by product, and I don't see a reason why the user should be prohibited from doing so. If they want absurdly-low-quality generation, more freedom to them.