Wouldn't that be convenient? Instead of having to dismount and remount everytime you talk to an NPC you can simply remain on your mount during the conversation. No need to play those mount/dismount animations (and sounds!) every single time you talk to someone.

If there is a problem with this due to handing over items and cutscenes, well, just dismount automatically when you need to hand over the items or the cutscene is about to start play.

It's a very small thing, but I feel like it would smoothen the mount feature AND improve the immersion - people talk to each other irl while on their bike, in their car or when riding a horse, so why can't we do the same in a fantasy game?