I think this is different from Watertown, in that the latter was originally housed in a gatefold. In that case, it should indeed be restored, because it's about the artwork being designed for the gatefold format. For an album that always had a single sleeve, I usually prefer that it remain so, even if there are two LPs in the sleeve. Now, whether it comes across as cheap or not will depend on the quality and thickness of the cardboard stock, whether or not the cover is tip-on, the quality of the printing, etc. All IMHO, of course.