Why is there no general trader in Morthal....?
Not even a blacksmith?

Doesnt make sense.....a capital of a Hold with no trader or blacksmith.

Pain in the ass too if you have a full inventory....as I have.
Back to Whiterun I guess.

I would suggest buying a horse. If you don't have the gold to buy a horse go to the nearby stable & sneak next to a horse if your hidden click to steal horse. No bounty will be added & you will be able to fast travel. (Be sure to fast travel to closest area to where you want to be.)

I always wondered that about Morthal myself.

They have an Alchemist, a Mage who can cure vampirism... and that's it. I mean, there's not even a stand-alone grindstone.

There's a grindstone behind the sawmill, and maybe a leather rack. But that's it.

Pretty dysfunctional place for the capital of a hold, and that's before you even get to their little vampire problem.