DoD could really use an "Item Set" feature. It'd be a few buttons or so on your character page that toggled between different sets of equipped items. I want to use my axe/shield for melee, but my double tomes for ranged attacks. Switching between items the normal way (by dragging and dropping) doesn't take any turns, so there's no advantage gained by having this feature. Another use is to unequip all negative items before casting spells. I do this a lot when playing Vampirism, because the corpse drink scales off of magic power. It's rather tedious to do this by hand every time.
That is the problem with Vampirism, and I reckon it'll get changed in the next version. Other than that, personally I don't care whether there are item sets (since, other than the really rare situations, I'm only changing equipment when switching floors or finding something better), but I do have to admit that the idea is good.
Yeah, I think David said he's going to change the scaling. There's a discussion about it in another thread. But that was just one example. I've played a lot of hybrid caster/melee characters in the past who wore a ton of heavy armor. Sometimes it was important to take it all off before casting certain spells to get the maximum effect. But more often, the double-tome ranged attack is the scenario I'd use this in. It's nice to wear two Kronged Malleus Malficarums and throw things at monsters. I'm surprised you've never done something like this.
I did it a few times, actually, but since I play just to have a few minutes of random fun, getting through the whole game isn't my prime target, and thus I only switch equipment like that when facing a zoo (and even then, since most of the time I just test whatever bits of code I infecter my DoD with, I rarely get to the deepest floors where such changing becomes more common) or something like that ("rare situations"), when I know for sure it's going to be beneficial to me.