Definitely food for thought here.
@Rouenpucelle, relationship could be very important. Occasionally my Sims had a single parent thrown in the mix, usually as an afterthought of sorts (e.g. to justify a teenager prepping for University). I am now thinking about how to create some family for a Sim without (necessarily) sacrificing the small household which can be micromanaged...
When Sims do seem to come from nowhere, I guess it's easy for their backstories to be superficial/lost/lack depth once in the game.
@SimsLovinLycan You make a strong point also. Sometimes I get over this by using the GTW careers, or something that can be done at home like freelancing, social media etc. I find they add some depth and challenge to the careers. I guess an argument can be made that even those become repetitive rather quickly...
My Sims are admittedly terrible at making friends. I realise now that I don't have them socialize in realistic ways. A big element which is missing is co-workers, friends, active acquaintances, family connections etc...
Maybe the missing element is relationships ?? :| But how do I fix that?