Lactose intolerance being a personality trait is just Disrespectful.

I could also go all the way back to lactose intolerance. I'm lactose intolerant, and getting that trait in the game, made me feel seen. That was small, but also important to me.

https://www.ea.com/games/the-sims/news/celebrating-25-years-of-the-sims-loel-phelps

At the same time it's unfair for people who have food allergies (Eggs, fish, ...), pollen/fur/feather/dust mite allergies, Celiac Disease (Gluten-related disorders), ...

And Glucose monitors without Diabetes trait is strange.

Hearing aids and glasses could have traits too, the sims would be clumsy and less efficient when these accessories are missing (implying Career outfit must include them).

I agree it's more health challenges than personality traits so it should be a separate thing.

I mean that they could make it into a separate category for medical conditions, because i have seen people who joke and meme about it as if it were a mental condition, the jokes often involves cruelty or violence against those who have it, which is just sicking.😟

Honestly medical conditions would work great as "reward" traits. I'm not saying having a chronic condition is a reward, god no,  I have some myself and would like them gone, but purly within the game's mechanics that would allow you to add minor traits to your sims that don't take away a personality trait slot. I am lactose intolerant but I never use this trait in game because it isn't a personality, yeah, and I'm not giving up one of three trait slots. Now, reward traits can be easily added in game and give small gameplay effects. Most of them are good, but I think the mechanic would absolutely work to add minor traits to sims that make the game harder, too. Let us set sim personality in cas and then hand us a few "reward" traits to further define the characters.

Or, that's probably better than the reward trait idea, make them like quirks for infants/toddlers, but on adults. Minor traits that can be added by the player and/or aquired through gameplay. Quirks could be illnesses, preferences, behaviours not tied to traits etc. 

I'm not keen on this in gameplay terms, it just isn't a big enough part of someone to use up a limited personality slot on it. I still think the personality/traits system in TS4 needs work on various points, and using things like this as an entire personality point is an example of how personality points aren't consist in meaning/influence which makes it hard to justify choosing some of them.

This sounds like a great way to implement it. Something like how lots have lot traits, but also a separate selection menu for challenges. It could be an extra category menu thing with similar mechanics to the trait selection menu, where you could optionally choose things like lactose intolerance, the conditions you've mentioned, and then some. There are really a ton of possibilities there

I would be in favor of having the lactose intolerant and vegetarian traits be additional traits that do not count against the trait limit, as is sometimes seen in NPC Sims that have 4 traits (or more than 6 if you have Growing Together). Within the structure of the game, they are traits but having them take up trait slots means that they take an outsized role in the Sim's personality, thereby limiting other traits that may be more representative of the personality. That's the biggest reason why I don't choose the traits myself; if I want a Sim to be lactose intolerant or vegetarian, I tend to just play them that way but save the trait slot for something else, which makes me feel like these are parts of the game that are just going to waste since few people will use them for the same reasons.