I've been watching the Freelance Astronauts' LP of Oblivion which has conjured up some pretty fond memories of those Oblivion and Morrowind in me. Perhaps it is because Morrowind had left such a big impact on me when I first played it and I've played Oblivion, Fallout 3, and New Vegas in the interim that I've petered out on Skyrim in a lot shorter period than I have with those other four games. I also get the feeling that the amount of mods hasn't quite lived up to that heritage as the Gamebryo games had; for instance, very soon after Oblivion was released, we had great ones like Obscuro's Overhaul, Deadly Reflex, and the Midas Magic mod come out, whereas with Skyrim I had sort of given up hope after finding that the armour and clothing mod categories at the Skyrim Nexus were inundated with palette-swaps of a certain piece of stripperific clothing nominally only available to a certain NPC in the game.
Or maybe it's because of the slightly more "generic fantasy" environments in Oblivion and Morrowind that I felt that it gave me more of a Tabula Rasa to work with for my character, and I find myself sorely missing the spell-crafting, enchanting, and alchemy mechanics in those two. Sure they were utterly broken, but the way I see it, the Elder Scrolls games are more toys than games to me.