Not sure if you want this sort of feedback; but I never use a controller. I do have an xbox controller and tried it once of twice but found it very klunky. What bugs the heck out of me is that most games with controller support have lousy kb/mouse support.

Witcher 2 (not top down); is probably the best game with combined kb/m and controller support but even with this game you can tell that interface with kb/m would have been a *lot* better if they hadn't mucked it up for controller support.
I can't really answer your question for demand but in practice I think a game requires to completely different interfaces not a single interface with two streams of input. How you present things for the kb/m crowd can fundamentally be different than for those with a controller (witcher 2 demonstrates this problem in how they manage inventory; the design is around a controller - and as I noted it is one of the best combined interfaces I've seen it is also clear they had to handicap kb/m to support it; I think what they shoudl have done (and you) is build two completely different interfaces (including graphics around presentation of things like inventory) and then feed the output of the interface into the game. This might be more work than you wish to undertake or the structure of the code might not support it (I've not seen a game do this yet; but perhaps there is an example somewhere).

Btw darksoul sucks not because I dislike the game but the control/interface is everely handicapped on the pc.