Another side thought based on the changes in TCoA and the decoupling of several racial features from races. Has anyone thought of a cool concept of a PC they wanted, but when creating the character, saw that the mechanics of how racial features didn't really support it well from a mechanical standpoint? I'm not just talking about optimization, but in general. With bounded accuracy, every modifier counts, so have you ever been swayed to avoid a particular concept that you would do if features were decoupled?
I mean really they're pretty countless but the biggest one is like "Genasi/Anything" for me. There's tons of times I wanted to play a Genasi in 5E, but didn't, because they have weird modifiers AND totally rubbish racial abilities.
Or Kobolds. I love Kobolds. I'd love to play a Kobold. I'm not, however, playing a race which has a totally unnecessary penalty that other races don't have, and nothing to make up for it - and less than +3 to the other stats (including no +CHA which means Kobolds don't even make good Sorcerers, despite it being the classic combo). Terrible racial abilities top of that too.
Clerics are dreadful for this because virtually no races I want to play a Cleric of have +WIS. I have got past that before, but pretty begrudgingly, I can tell you. Druids don't have it quite as bad but it's not great. The lack of +2 WIS races in general is kind of "a thing".
I could go on. Every character I've created in 5E included me considering and dismissing certain races because they didn't have any applicable mods, despite seeming like a cool concept. Whether I'd have finally picked that race is another question, but I think I would have in at least some cases.
A Stout Halflings is actually not bad for a Barbarian: Longsword held with both hands is a solid d10 still.
Not bad isn't really the same as good, though, and as you go on with playing them, the situation gets worse - the Halfling can never get GWM, which if Feats are in the game, is going to be a huge source of damage to any 2H Barbarian with the faintest hint of optimization.
That said the characters i remember the most aren’t the highly optimized ones, it’s the strong conceptual ones even if they are a little weaker.
Trouble with this is, remember and enjoy playing are two different things. There are several totally ineffectual characters my group remembers really well. Pretty much none of the people actually playing them enjoyed them in the long term, though (and every single one of them had a short career). We all remember the rubbish Dragonborn Assassin who ended up getting thrown out of an airship, perhaps better than we remember the hyper-competent Dwarf Cleric. Reason she got thrown out of an airship though was that the player was just totally done with playing her. And we don't remember either as well as the exceptionally well-roleplayed Gith (I forget what kind) Shaman (who was secretly highly optimized).