The Elder Scrolls 6: 11 Past Mistakes Bethesda Can't Repeat
5. Failing Quests Because Of Specific Scripting Bugs
Part n' parcel of the general "get a new engine/fix the bugs/sort the animations" qualm, if there was one specific thing that directly gets in the way of our enjoyment (besides faces falling off), it's the scripting bugs.
Assumedly down to Bethesda's otherwise genius radial quest tech (where the game will generate a quest to take you somewhere you've not visited yet), this often results in things like enemies being locked out of the world geometry, or followers falling off cliffs.
Whilst things like a backwards-flying dragon or a market seller being comprised of nothing but a floating set of teeth is perhaps "part of that Bethesda charm", actual game-breaking bugs are no laughing matter.
The only solution is to reload a save (if you can) and hope for the best, which isn't remotely an acceptable practice.