Can't Skyrim attempt to mimic how Oblivion handled things? The engines are, fundamentally, very, very similar.
I don't think Oblivion does handle anything different, it's still the same engine and the same save system.
Maybe Oblivion just has a more aggressive clean up, but more likely it's because Oblivion is simply "smaller", less quests less content less important NPCs and so on.
To mimic Oblivion with Skyrim would mean to remove content from the game. Probably not the best way to solve the problem.
Hopefully a more aggressive clean up to remove dead bodies and other unnecessary data earler from the game is sufficient enough, otherwise I'm not sure if the problem can actually be solved and with upcoming DLCs it should only get worse :/
Let's hope they find some ways to free up more RAM and hopefully use a new engine (a real new one -.-) for their next game.