Well, it's always better to ask for more and get less, in case you ask for less and get even less than that...Besides, generalization is a horrid tool in majority of the discussions. It shouldn't be used as an argument.
Well, the least problematic option would be allowing a choice between the two. If you change the default, then those that are happy with current state of things will get pissed.
Honestly, that depends entirely on how the game graphics work behind the scenes. It could very well be the case of developers "using a slider" (kind of) to generate that non-slider image of the new one-of-a-kind on everyone's behind, and then just "saving" it. Alas...developers at every step seem to complain about extremely horrid engine and legacy coding that no one in their right mind would use for anything but an hour long or so indie game, let alone large MMO title...But hey, there are exceptions, right?!...