As real life card maker, I'd love to see them add a scrapbooking/cardmaking skill (they kind of added it in seasons, but just for kids). Then with GT we could make a scrapbooking club and hold a crop :)
Also would love a bunch of new furniture/clutter to create my own craft room in game.
Other hobbies I'd love to see:
Jewelry Making - Another use for those gems you can dig up
Pottery - Maybe even connect it to seasons to use for floral arrangements
Karate - Was my favorite part of sims 3 and would love to see it back sometime
Sewing - Would allow you to unlock new outfits which would improve in quality as your skill raised
Candle Making - Use flowers and fruit to scent them and different combos would trigger different emotions
Drawing - Probably isn't too different from painting, but would add variety
Canning - Make pickles, jams, jellies, or just preserve harvestables for a rainy day (would love to see with a farming pack)
Nectar Making - Would give more uses for harvestables, and different combos would trigger certain emotions
Knitting/Crocheting - Would give elders (or really anyone) a hobby they could do while watching TV
And of course with all these amazing works of art being produced, a craft fair where you can sell them is a must. Would love a hobbies expansion pack with a new town, so that the central common area could hold intermittent craft fairs (like city living).