Ugh, I'd forgotten after all these years, but this complaint is now fresh in my mind. In Morrowind, never mind the NPCs' AI is rudimentary at best, i.e.: everyone tends to wander in the same 20 square feet at all times of the day if they're not stock still never moving at all, when they DO wander, the love to plug up hallways and doorways, and when you approach them trying to get by, it triggers an automatic "focus on the player" behavior that leaves them stuck in place until you move away to await their AI to move them freely again. Collision is terrible, so obvious gaps that might merit a polite "excuse me" in real life turns the NPCs basically into walls you can't get by.
I took a guess and looked it up on YouTube for evidence of this behavior, and sure as shit here you go. I'd like to say this is an infrequent problem, but it happens ALL THE TIME. I've got an NPC stuck (doesn't wander) in a hallway in a Mages Guild I use frequently for fast travel who hangs me up EVERY. SINGLE. TIME I try to pass through. It's so bad, I've thought about killing her, but I'd forfeit my standing in the Mages Guild, and I'm pretty sure pissing off he people that can teleport you around isn't good business. Not a game breaker, but certainly something that bothers me.