do you want become infected?
the answer is probabily yes, sometimes, because those skill line give you almost an advantage and you can always have a cure.
there are not heavy penality to be vamp or lycan in eso: vamp are weak to fire instead of lightning, no wewakness on daytime exposition.....
what make me think about immersion is if you get your main character infected and if there is no cure at all for advanced stage of disease, you probabily going to have a different approch.
so my proposal will be at least to:
- make permanent the final stage of vampirism and lycantropy
- enable the cure only for the first level of the infection
- debuff the power in day time for vamp and heavily buff during the night
and many many other....
this should make the role playing really immersive, with buff and debuff, as the tradition and lore require.