I'd be entirely on board for more adjustable difficulty settings - and, critically, for said difficulty settings to be something you can change without starting an entire new game.
(While it'd probably be pretty trivial to mod something like this in, I do feel strongly that 'adjustable difficulty' is something that should be part of the base game. A new player isn't likely to be running mods, after all, and new players are the ones who'd benefit most from being able to decide that, well, actually, they really should have been playing on easy, without having to start an entire new game.)