Thing is, Backwards compatibility (in this context) is a Microsoft feature they designed to allow 360 games to be played on the Xbox One. It's up to Microsoft which games make the list, Not Bethesda.
Although backwards compatibility would certainly be well received for Oblivion a re-master across all 3 platforms would be much, much more welcome.
I do think that Bethesda does have a say if it is available for it or not.
Oblivion is the only reason I kept my 360
I think real 'Hardware Banging' as you described above died with Amiga, Console games are made on dev kits/PC's etc and I doubt Microsoft would allow any unknown 'proprietary' code to run on their system.
Ultimately the backwards compatibility on the Xbox One is actually NOT backwards compatibility at all despite what Microsoft claim. The entire 360 OS is emulated in a virtual box within the Xbox One which is why they games need modifying in the first place, They require a wrapper of some sort and small changes to iron out performance issues etc. the actual game code itself requires very little if any changes. (Or so I've read anyway).