Villager interaction:
Not a quality of life option per se but ... let the villagers interact with outdoor items or at least Nook Miles items. You can design the cutest playgound, the coolest outdoor gym or the most beautiful campsite area but everything seems so lifeless since no villager will actually interact with anything. Yes, they will sit on a bench or on the jungle gym but nothing else. Makes me sad and it is definetely a missed opportunity to breathe some life into villagers and the island life.
Villager dialogue variety:
Love the little personalities and how every villager has a style (play, nature, music, etc). But they still repeat the same mundane things over and over.... Yes, I got a lot of fossils assessed yesterday. Yep, buried some bells and caught a lot of fish... That's cool dialogue the first time a villager says it, but if two or more villagers make a comment about it the same day... it gets boring. Love the games decoration options but the villagers could have been more fleshed out.
Shopping for clothing items:
For quality of life changes I'd really love the option to buy more clothes per visit of the dressing room. For example, "press the Y button to add an item to your cart" or something along those lines. It's a hassle to have to visit the stall four or more times in a row just to get every color option of a clothing item you like. Similarly, why do I have to remove the wand outfit first before a purchase?