Personally I would find it very boring to remake a game, so I could see how Shidiwen would get tired of it if he did in fact stop. Using the editor is tedious enough, might as well do something creative with it instead of recreating something that already exists (and is already very good. I could see remaking a game like Planescape: Torment which notoriously has terrible combat and gameplay but amazing writing, where you're trying to improve upon the weak aspects of the game while keeping the good content.) Of course, I'm sure Shidiwen is/was adding and reworking tons of stuff for the D:OS engine anyway, so it was still a creative endeavor, but just not my cup of tea.
Yes, as you kind of convinced yourself along the way, the two are not mutually exclusive.
A good example is the Ultima 5: Lazarus remake. Depending on the game, there is a lot you can potentially do (especially with older games) to flesh out stories and build on what's there with a fresh twist. There is still plenty of room to innovate and be creative.
