If the game is good, why would it need mods?
See I think among none mod users there is a misunderstanding about what mods are for.
As I see it mods are about 2 things
1) Adding massively to the number of man hours worth of work a game has spent on it in terms of content to play with. No matter how big a game is and how long it is in development it will only ever have a finite amount of developer hours spent on it, releasing mod tools allows the community to continue adding content to the game for years to come. The net result of this is a massively increased amount of content keeping the game fresh and interesting. Total up all the man hours spent by mod makers working on adding contented to Oblivion and I'm sure it would hugely exceed the number of dev hours spent creating the game in the first place. This can only be a good thing for the game.
2) Tailoring to your tastes. The great thing about people is we are all different, some people enjoy managing every little detail others are only interested in the big picture, some want to struggle and battle against a harsh unforgiving world, others want to stride through the lands as a god among men. It simply isn't possible to allow for all these different play styles and preferences and spend valuable dev time inventing multitudes of systems to cover every type of game play (and then offering the option for them to be turned off for players who don't like them). Mod makers however can focus on creating these systems to enhance their own play and share the results with other. Its about customising your experience and it is a wonderful thing.
I am pretty sure that the management and devs at Bethesda know this full well and have every intention of providing at least as much mod support for the next elder scrolls game as they have for the past 2 (plus fallout).