Agree.
Bethesda isn’t just making games. They’re making gorgeous, fascinating sandboxes and handing to their customers a lot of control over what’s in those sandboxes. As most game studios are pulling back from handing over the keys to their gaming kingdoms to players, Bethesda is pushing forward with it, even to the point of letting *console users* add mods – whoever expected *that?* A useful contrast is with EA/Bioware, which carefully meters everything the player experiences down to the gold piece and experience point and which has eliminated player modding. Bethesda empowers the player. EA/Bioware empowers itself; you play their way or not at all.
Obsidian did a fine job of walking in Bethesda’s footprints with FONV, and some of the finest mods anywhere have been released for FONV (New Vegas Bounties I and II come to mind, among others). I’m hoping Bethesda will let Obsidian have a crack at making a FO game using the FO4 engine. It’s a very good fit; Obsidian has many early FO1 and FO2 developers on staff.

In addition to it not being in Bethesda’s DNA, its not in their games’ DNA. Whereas most companies drum out 13 hours of fun for $60, Bethesda gives you hundreds of hours and still has new customers decades after original release (See: Morrowwind). It’s like comparing the works of Stephenie Meyer (Twilight) or R. L. Stine (Goosebumps) to Leo Tolstoy (War and Peace) or, more aptly for Fallout, Sun Tzu (The Art of War).