I just made a throwaway post about this, but thought I'd start a thread before I or someone else thinks of all the reasons it's a crap idea.

But if there's a possible lycanthropy perk tree, why not a vampirism one? This could build to make vampirism actually desirable if you work at it. Doing vampire stuff - svcking blood, casting vampire spells, seducing maidens or whatever. So you get more resistant to sunlight & fire, get away with being stage 4 without being attacked by everyone, get a boost to existing powers and maybe even new ones. Culminating in being able to be the vampire lord we saw. Vampirism could become a genuinely attractive option, but only if you invest in training yourself to be the best at bloodsvcking lord of darknessing.

I already like playing a vampire in Skyrim.
I find that the need to manage health/ stamina/ magicka carefully (when in sunlight) and the need to feed make it a sort of hardcoe mode.
I enjoy taking heed of when its day or night and making sure people dont find out Im vampire by never going to stage four.

But, I would enjoy a vampire perk tree.
I just dont agree it should remove all downsides of being a vampire.
I can imagine for instance a really powerful (and optional in the tree) perk that also has a downside of slightly increasing your weakness to fire.
Some perks that would allow you to be an even more powerful mage would also be helpful.

And as part of the general package, the vampire drain health spell should scale to level.