Oblivion:
YES - Seriously, Oblivion's story was really weak. I'm all about the story in games and I'll put up with a lot of bad gameplay/graphics etc, just for a good storyline. BUT there was so much going on in the background of Oblivion that the story quests themselves were mostly redundant. I've spent sooo many hours and leveled my character up so far without even touching the story on some playthroughs. As for those damned Oblivion gates... urgh. But really, some of the side quests had much more interesting plots than the main story anyway!
New Vegas:
NO - NV's story was actually quite interesting and was of personal interest to my character unlike Oblivion which was all some crazy destiny crap. My character felt compelled to find out why he was shot and buried alive and hell, if he wanted to take over NV for himself, he could have done. But the real hook for me was that the side missions actually affected the story too. Do some missions for the Legion and you piss off the NCR, do the House missions and you run the risk of pissing off the NCR too. Carry out the NCR missions and you'll shut away the House path forever. Follow the instructions of a certain 3rd party and you can pretty much screw everyone over. Plus all these missions mixed together and made you really stop and think what you were doing, why and who it would affect. Shame about the bugs.
So in short, NV's story was very important to the overall atmosphere and experience, while in Oblivion you could happily run around picking flowers and raiding dungeons without a care in the world. Both great games but better in some areas than in others.