Please look up the information regarding creating a game engine and stop posting that it can be patched. It can, but for every kilobyte of data that would get changed, tons of game data would have to altered to accept and use the new adjustments. Now with all of the problems this game has, It would take a couple of months (if not years) and tons of Megabytes (or even Gigabytes) to essentially redevelop the engine and the game. That would be pointless, as the amount of time spent doing that could be used developing a completely new and far superior engine. Also, if they altered too much, it could make your game not function with your save, as it would pretty much be a new game, so it would be a moot point if you couldn't use the save you were trying to get fixed. The main problem here is that Obsidian decided to use the same engine as Fallout 3, which had already been showing signs of problems, and pushed it WAY past it limits.
Uh, what? I write code for a living and have been working with game engines on several occasions (right now as a matter of fact), so I'm quite confident in what I'm saying here and what you're saying is just plain wrong. Sure, if they'd add new features to the engine (like a new animation system), then they'd need to change some of the assets as well and then you'd be partially right. But for bug fixes? No. Since a bug fix shouldn't change the behavior of the engine except make it work as expected. So, yea.. you might want to look up "the information regarding creating a game engine" yourself, mr.