A lot of us regulars never really left Cyrodiil, myself included. I can still remember the moment on 11/11/11 when I exited Skyrim's beginning dungeon, and I thought "I love Skyrim, Skyrim is amazing in many ways, but I still want to return to Cyrodiil". So I never really stopped playing Oblivion.
To me, Oblivion's graphics are fine. I don't see them as 'lesser', I see them as different.
And so far as gameplay goes, that's one of the reasons I still love Oblivion (while also loving Skyrim), the gameplay is similar between both games in many ways, but both games also have plenty of variances. They've got completely different approaches and philosophies with many things. Makes each game feel more unique.