A big quality of life feature I think would be nice would include being able to save/load character/outfit/etc. templates into the program without having to load up entire characters themselves each time. You can sort of do this if you alter the default character in settings, but being able to save your own set of default outfits/bodies would be useful.
In the more long term, being able to separately scale height and width of sprites, or even being able to separately scale the different parts of sprites someday would be amazing. Sprites' eyes being able to "look" in different directions would also be nice. Being able to have different types of eyebrows/eyelashes, or reshape/rotate the ones we have now, is another idea too.