I'd say Juggernaught is like Myst on Acid.
Nothing like D. D is one story, but Juggernaught is comprised of many sub stories that tie in together. Very clever in my opinion.
As for D, those 2 rooms are not total time wasters. You need to play those rooms to get the secret ending. Witch ties into the never released/scrapped D2 for the 3D0.
D2 for the Dreamcast was a different game though brillant.