I agree that most Skyrim dungeons were quite linear, but they never felt repetitive to me. Each had a unique layout with a compliment of enemies that made sense for the location. Yes, they were often Drugar heavy, but most of them WERE ancient crypts and tombs, so it made sense. I certainly felt the Dwemer ruins were always well done and certainly unique in both layout and design.
Technically, Blackreach wasn't a dungeon at all but a series of highly modified external cells.
Oblivion's dungeons not only felt repetitive but were highly copied and pasted from a very limited layout selection, so I certainly don't consider them better. There was some branching paths that Skyrim lacked, but that was usually more frustrating than exciting.
OT on Blackreach: I just found out last night that you could get into it without doing the Lexicon quest...found one of the other entrances and the stairs opened up with the orb thingy (I did have that in my inventory already). I have over 1200 hours and still find out new things.