I would pay full price for Fallout 3, New Vegas, Oblivion if they would simply fix the bugs and re-release them to run properly on modern systems. (And I'm one penny pinching MF)
I would guess they don't do this because they're worried the community will freak out about the update breaking mod compatibility but they already kinda did this with Skyrim when they released the Enhanced edition or whatever they called it.
There has to be money on the table here for them. If modders can fix their games without access to the source code then it couldn't be that labor intensive to hire someone to go through the code and fix it right?
I just don't get it. Are they maybe worried the old games will cannibalize the audience for their new games or something?
I shouldn't have to beg these assholes to be greedy. This is America god dammit. 
they might actually be remaking Oblivion, according to rumor. but that's a remake, and i think the 'proper' way to do something like you suggest. contrary to the notion "it couldn't be that labor intensive" there'd actually be a shitton because these are really big games, and wrestling with stuff like new operating systems and hardware isn't trivial either.
so if you're bothering to put a bunch of people on a big project, why not make this a total replacement you can legitimately charge full price for? that will have a new lifespan, probably with mods & (bethesda these days) paid mods
I don't want the gameplay overhauled. If they want to create an entirely different game and charge 60 then they are welcome to do so. I just want the game that is already a smash success to be playable and that is such a smaller investment in resources. I may be biased but I don't want Oblivion to play like Skyrim.