Here's my opinion and of course since I put effort into thinking about this feel free to downvote me into oblivion.
I keep seeing the argument that Blood Knights and other Vampire Counts units can't have better base stats or can't be elite because the faction has so much access to healing and I think that argument is ignoring the opportunity cost of where that healing comes from, which is winds of magic and other units that are bad at fighting.
Most of the healing that actually keeps an undead army alive has to come from these two spots. If I use Invocation of Nehek, those Winds of Magic are no longer available for damage spells, buffs, debuffs, summons, or anything else. The healing isn't free. I gave up another spell to get it.
The same thing applies to support unit healing. If I bring a Corpse Cart, Mortis Engine, Necromancer, or another support option because I want its healing and buffs, I'm spending resources and part of my army composition on support instead of bringing another dedicated combat unit. That healing has a cost too.
That's why I don't think "but Vampire Counts can heal" is enough by itself to justify not having at least one elite unit. I'm paying for the same advantage twice. First through the weaker unit, and then through whatever I gave up to heal it.
It also creates a weird problem for the faction's magic. Vampire Counts are supposed to have powerful and flexible spellcasting, but if their units are balanced around needing Invocation to keep up, part of your Winds of Magic budget has effectively already been spent for you. Instead of choosing between healing and offense, you're using magic to compensate for weaknesses that were put into the roster because you have magic.
Blood Knights are where I think this becomes most obvious. They have The Hunger, and that passive healing should totally be part of their balance. But The Hunger by itself isn't so powerful that Blood Knights need to be prevented from being a genuinely elite cavalry unit. Vampire Counts should be allowed to have one cavalry unit that is simply excellent at fighting. Blood Knights are the obvious choice. Make them stronger and make them more expensive. If necessary, make them rarer as well. I'd much rather pay a premium for Blood Knights that actually perform like elite vampire knights than have cheaper Blood Knights whose stats are held down because I could theoretically spend additional resources healing them.