Thats... kinda the point. Contrast two announcements at fanfest, one is 'Hey we're doing Necromancer, it's a caster and it's focused on summoning many minions to do chip damage to your enemies' (like 80% of media shows Necro to be). The other is 'Hey, we're doing Necromancer, but in our own twist, we're making it a healer'. Nothing about it being a healer prevents it from summoning minions, but the fact it's not 'damage dealer Necro' sets it apart from the rest of the market. Of course, some people might not be too happy that they're forced to play healer to enjoy Necro, but the same happened with DRK, the same happened with BLU (everyone got screwed on that one), heck when it was first being teased I thought the best role for RDM would be Tank (mix of magic and melee, can equip chainmail in FFTA, etc)
For gameplay, I don't see how the engine is too rigid. Consider for example, it has a 123 called Soulsplit, Soulreap, Desecration (or something edgy like those). You use it, and it has the additional effect of 'Fills the Necro-whatever Gauge by X/Y/Z' for each step with the finisher doing more. You can then, once you have 'stolen' enough life energy via damage spells, use it on healing skills. If you know WOW stuff, Holy Paladin has Crusader Strike and Judgement, right? Both generate one Holy Power, and three HP can be spent on essentially Solace or Rapture (their AOE one is a cone though). So generate, say, 20 gauge (so you can pool up to 5 of these 'stolen heals') and have a ST heal and a cone heal (or a circle ala Rapture if you don't want positioning to matter as much)
IDK about calling something 'blood mage' either, it's kinda just... eh, as far as names go. Besides, it'd also imply it works specifically with blood, which some enemies (ghosts, spirits, zombies, skeletons, machina) don't have. Necromancer being able to manipulate life energies would at least explain the first four of those. Creative liberties would be needed to explain other things like machines I guess. But the point of using the name Necro is because it's a job from previous FF games (5remake mainly where it was 'BLU with a twist' basically), I don't recall a 'blood mage' in any games. And again 'Necromancy' has a much broader scope imo for what aesthetics it can do, whereas blood magic, if anything, sounds like a sub-school OF necromancy.
I have heard from little starbirds about forbidden techniques to allow your WHM to have a blood magic aesthetic, which can be found on a distant world called 'Youtube', IF SE let us have quests to unlock 'skillset glamours' eg a Nier themed SGE or an elemental GNB (lightning shot has actual lightning effects, burst strike looks more fiery, etc), or a 'redeemed DRK' that has light themed skills, a dark edgy WHM that uses these 'blood magic' animations I've heard about would be cool
No, it's the whole raid, but if you're in a party (so, dungeons), it's healing per tick is doubled to compensate for the lack of 'extra targets' for it to hit. Same for Evoker's Rewind (Macrocosmos, but without the 'press to apply buff' part, it's just instant), and the Priest one I don't remember the name of (might be Divine Hymn, might be Symbol of Hope, it's one of the two). They only just, this expansion, gave the same treatment to Monk's Revival, can you believe that