I understand that the Dragon priests are supposed to be the liches for Skyrim, but why would they remove the "normal" lich from the game anyway? the ones from Oblvion where nether liches and more daedra than the usual undead magic user concept, but they were a pretty cool enemy to face, sor t of the elite undead magic user...I kind of miss them

get to level 81 and they start to appear in place of draugr
if you get to lvl 81 before you do the first quest the draugr you fight for the slab is a dragon priest
they just dont have masks

Eh. I like the Dragon priests better, but I think that there should be more of the damned things.

Many draugr use magic, and some of the stronger ones can be quite difficult.
Yes, most draugr just use combat, but the magic wielding ones can be seen as a "replacement" for the lich. (since having magic-wielding undead draugrs and lich would just be redundant)

Also, this isn't Oblivion. A new game doesn't need to fit the same archetype as the old game.