Bethesda's number one consideration when it comes to engines is will it support a large open environment with a large number of NPCs and items. Brink and RAGE aren't set up for these environments so it wouldn't work for an Elder Scrolls game . . . at least not in the core series.
SMART is neat and I could see including something like it if it was combined (and scaled) with the acrobatics score. The differences in armor weight even match up well with the differences in Brink's character size. You certainly wouldn't want a system like this available from the get go or every character will have the ability to bounce all over the place.
And Brink uses id Tech 4 (id Tech 5 is Rage's engine), that engine isn't suitable for open world games, a Bethesda developer (Todd I think) said this in an interview. That Gamebryo is good for huge RPG games and that id Tech engine is good for FPS games in enclosed environments rather than big open worlds.
Technically I believe Brink uses id tech 3 as it's base although it's so heavily modified none of the engine remains untouched.