Way, way back, when 3.0 was pretty darn fresh, Kenzer & Co came out with their Kalamar stuff, in which several of the critters would have little notes in them like, 'Unlike other Aberrations, this critter has Blindsight instead of Darkvision' or whatever.
To me, that was the way it was *supposed* to be. Yes, Undead have good Will saves, poor Reflex saves and poor BAB, *except* if I say so, because this Skeleton Warrior has Full BAB.
The type thing, IMO, was supposed to be a quick and easy 'pre-template' that the monster designer would just modify to suit this particular creatures design needs. Entirely too many people, unlike the Kenzer & Co crew, seemed to regard creature types as a straightjacket. Instead of saying 'This undead has a better BAB' or 'this Aberration has no darkvision,' they seemed to feel utterly helpless to modify the monsters they were creating, to the point where it was regarded as almost revolutionary when, years later, somebody made undead that had bonus hit points from 'Unholy Toughness' or whatever.
Maybe I was spoiled by that Kalamar stuff, but I always thought that Type was supposed to be a guiding framework for me to build off of, and that if I wanted a monster to have bigger or smaller HD (a more martial fey brute or a less physically imposing slender willowy 'wisp dragon'), then I was free to do so without having to kludge together stuff like class levels or special compensatory magic items or 'unholy toughness.'
Creating a whole new tier of 'types' based on 'role,' is, IMO, just another step down the false path of tying the hands of the monster designer. Maybe this creature is both a spring *and* an autumn, and can serve as a leader to it's minions *and* is still a kick butt melee combatant when they fall and it's down to the wire.
