Doomed and Archmage both benefit heavily from it, Doomed because their range on everything not-Shadows is crap and they're not concerned with fatigue very much, and AM because high fatigue is actually GOOD for them to facilitate easier dumping of the mana bar for Disruption Shield. A similar point to Doomed could maybe be made for Cursed but Cursed has much better prodigy options.
20% fatigue isn't really even all that bad, especially if you run light armor and naturally have 0 fatigue.
Yes, doomed has crappy range, but why increase range if they can get better stuff?
Can't comment on fatigue. Nice point. But range isn't a problem for archmage.. An inversed benefit compared to doomed's case.