Interesting question. I definitely think certain DLC can be combined under a theme. I think the moment EA began to recycle themes for EP was the moment when many felt we were ready to move on to sims 5.
Seasons stands on it's own, I can't place it anywhere and if feels so essential it should have been basegame
Work: Get to work, businesses and hobbies, Dine out
Supernatural: Realm of Magic, Werewolves, Vampires, Get to work, Life and Death, Paranormal, Crystal Creations, Romantic garden (wishing well) spooky stuff
Animals: Cats and dogs, Horse Ranch, Cottage living, my first pets stuff
Family and generations: Growing together, Life and Death, Parenthood, kids room stuff, toddler stuff, nifty knitting
Education: University, High school years
Holidays/Vacation and adventure: Island Living, Snowy escape, Outdoor retreat, Jungle adventures, Strangerville, Batuu
Hangout with friends: Get together, bowling night, movie hangout, backyard stuff
City and apartments: City living, for rent
Love: lovestruck, my wedding stories
Realism and lifestyle: eco lifestyle, dream home decorator, laundry day, tiny living, bust the dust, cool kitchen, home chef hustle, fitness
Fame and luxury: Get famous, spa day, vintage glamour, Moschino
No unique gameplay: luxury party, perfect patio, all kits except bust the dust
Notes:
- These are all my personal feelings. Others might disagree
- seasons stands on it's own, I can't place it anywhere and if feels so essential it should have been basegame
- Get to work and life and death are mentioned twice because they feel like hybrid packs with occult and realism combined. Both offer and occult. Why not the same for Island living? Island living only offers one minor occult. Get to works adds an alien world to visit and a scifi active career. Also kudos for including alien forms for younger age groups, which is sorely missed for mermaids. Life and Death offers a spooky neighborhood to live in, rebirth, tarot collection and an active career. Island living offers nothing for mermaids except their bare existence. Even for their gravestone they had to rely on life and death.
- No unique gameplay: luxury party and perfect patio lost their meaning then their objects were added to other packs and base game. This entire category should not exist in my opinion, but it does.
- supernaturals seem well represented but in sims 2 and 3 there was something supernatural found in every pack, with a massive supernatural EP in sims 3 as cherry on the cake. They were sprinkled throughout the entire DLC which I preferred. The occults in sims 4 are great but the pure realistic content droughts in between are awful. I preferred the sims 2 and sims 3 approach. I hope game packs can return.