Suggestion for Increased QOL

Sims QOL enhancement, bug hunting and increased sales.

I own all of your Sims 4 DLC.  I suggest that you make several of the older expansions part of the base game so that current and future DLC have increased added value and deal with squashing bugs.  You can even charge again for the base sims game maybe 20 bucks while leaving a demo version of the current base game that can't be upgraded.

Seasons 

This should be base game and essential.  Every DLC can add enhanced seasons, events and holidays. For example, the upcoming Fairy DLC could have special weather events peculiar to this magic realm adding depth to the DLC and fleshing out the region further with look and feel.  This allows you to add more value per DLC instantly with this as base game.  This can also help diversify the neighborhoods setting potentially strange weather events accordingly to enhance the neighborhoods story and look and feel.  Every single DLC should add a Holiday event or a few extra add on holiday options for the players to use.

Cat & Dogs - People love pets.  

Adding pet items per DLC integrated into each DLC in some ways is a massive positive to the game.  People love pets in real life and in the Sims.  Adding special additions such as fairy dogs/cats with wings for your pets would have been a big selling point and maybe they can do some funny fairy magic interactions while finding peculiar pets around town while integrated into the packs as makes sense.  This also allows increased interactions in all DLC related to pets as well as adding value with potential new skins or pet items which instantly adds selling value to a DLC.  For example if you had a special setup for a Farm dog interactions for Henford on Bagly and maybe even related challenges and interactions with dogs.   In life and death you could have had a soul guardian cat that protects family sims from death or does funny interactions with the Crow.  Pets add massive value per DLC by the nature of being able to add more depth to them even if there are just a few special interactions.  Players love seeing their pets interact and be part for the whole Sims world, not just the DLC one they originated in.

Get Together - Clubs.  

You really should add features for clubs in each DLC.  Pretty simple addition to add more value to all DLC's.  Clubs are a great way for players to get sims to do things together versus wandering off.  For example, you could of created Highschool clubs for each after school activity that allows more active event type setups that would be far easier if this was integrated into base game.  Even just adding new club enhancements per DLC requires likely less extra work as it's mostly code you already use versus new asset art and animation designs while adding instant value for all DLC using this code.  Clubs were an excellent edition and should have something special per DLC.  Also, this code can be expanded on to assist with helping sims do event activities together behind the scenes as the base code mechanics would be in all DLC teams creating content without having to cross talk with other departments as much.

Other good options for base game to enhance all DLC and gameplay:

Parenthood - Fits base game vibe of generational play.

Just adds a ton of value to the game.  The Sims is a social game and generational.  I say support that feature and make it available to everyone.  Generational gameplay is very popular so make this base game and maybe create a DLC that focuses on generational trees and fun generational celebrations and gameplay that people do already with challenges and such.  Would be great to have a generational tree artwork.  

Dine Out

Base game fix for events such as dates and eating out so the Sims stay together and eat together when out socializing without running off to do other things.  Being able to reserve a table and so on such that it is base game and functions over all product lines cleanly.  This can also have special mood breaks and depth if done right creating optional depth to all DLC with moods breaking a sims event interaction in a meaningful way that makes more sense for stories and interactions.  Cleaning up having dinner with a date, a drink at the bar, and or socializing with friends and family while having a meal on the town making sims a bit stickier as a group where it makes sense will help the game feel a bit less clunky and cleaner. This would also allow you to manage events better by sort of having sticky type activities such as dining, drinking at a bar together, using a Karaoke machine and so on out on events together.  Just seems like a good place to start is Dine Out as most players like the idea of going out to eat, drink or such and at least having the main event work and then after it can go chaotic.

Final Thoughts

If these were base game and cleaned up it would allow you to streamline much of the sims 4 experience and instantly adding value per DLC you wish to sell.  I'm sure some DLC doesn't sell as well but adding value through this older piece of code and being able to add extra content like a new pet skin theme, new club additions, odd weather additions, holidays per and more controls for events the players can customize on top will increase the value of all your DLC.  This opens up all DLC to have far more additional content with less asset cross confusion for your teams working on different projects as the base code would be available to adapt and sent out to everyone for special type gameplay and events to be added in.

Just my suggestion for a major QOL that will add major value to the game and likely help you sell more expansions and can let you revisit older ones adding a few tweaks to get their sales up with some simpler content that isn't necessarily art asset type data additions but more just code that is now available.  If you teams know they can count on Cats and Dogs in their DLC they can add value with animals into their design of those regions and some special interactions that make sense knowing that that content hits all players generating more value instantly to get the newer packs.

Love the relaxing game.  Love the creative aspect.  Love the silliness to escape into from this insane world.  Nice work with the latest expansions and trying to integrate more DLC together.  I say make it easier to do so by moving several of the highly valuable like at least Seasons as a base game.  And consider Pets as well as I would love to see pets be integrated into all DLC cleaner with a few more options.  Don't be afraid after doing this to add value to any DLC that lacked sales by adding some Pets, Holidays, cool event ideas that would get Sims Influencers talking about those older expansions and saying they just got to have it now.

Just my 2 cents.  Take care devs and gamers alike.