Which traits are so disappointing that it's not worth using them?

Clumsy. It always bothered me that Sims just "laugh at themselves" instead of getting Embarrassed. I think it's been tweaked at some point so it's a tiny bit noticeable now, but it's one I always felt didn't do much. 

Oh, also, I agree about Evil. Evil was always a little disappointing, as Mean seems more Evil than Evil, lol. I've given several of my Sims the Evil trait though because the laugh is funny to me and it amuses me to see them smile when another Sim is unhappy, lol. 

Another one I'd choose that's a nothingburger is the Good trait. Does that do anything at all besides react kind of negatively to Evil Sims? I hardly ever use this one. 

Recycle Disciple (eco lifestyle) sims with this trait want to regularly recycle items. If they haven't done so in a while they might autonomously do so. Imagine the sim would choose a valuable collectible or crafted item, just gone without a warning. I do everything I can to avoid this trait. 

If I am going to add CC to my game, it is usually traits. I too think the traits that came with the game do very little for real gameplay. Adding traits have helped, by having more variety, but only a little. And that is a shame. With a little tweaking, I think it could spice up gameplay alot if the traits affected gameplay more.

Cheerful, I don't suppose its completely useless trait, really, but as I play premades I see that one used far too often on far too many sims so I keep destroying all cheerful sims I come across 😆 like either they're bout to have some gloom in their way or the cheerful trait is more so...strangerville style addition to my story 🕶

I like Evil sims to be scheming and secretly corrupt so to me it makes sense they wouldn't reveal their evil in all situations and kind of appear polite at first meeting...I mean what evil plan really succeeds if you're like " hi im evil nice to meet you" 😅 well, unless thats some reverse psychology trick I suppose

but mean trait I totally feel like the sims should just be intensely mean to people for no good reason kinda like your regular bully with no elaborate schemes

It's pretty wild that sims 3 had traits doing way more since the day of it's release, and that it all barely does anything in Sims 4 even after what, 11 years or so now? 

The most important thing to make unique sims, and it's not a priority at all, like they don't see it as a problem that needs fixing. Like they never played sims 3. 

Sure Sims 3 had some near useless traits too that barely did anything, but pretty much all of them had quite an impact. It also did not lock an essential trait like brave behind requiring aspiration points, and had a nice opposing cowardly trait as well. 

I guess it is just something they don't know how to fix in the sims 4 engine.