IME the mechanical fiddly bits encourage fixation on the tools and rules and not so much engagement with the world.
Well, for me there is no engagement with the world without tools and rules. The rules are the expression of how the world works, and without that, I find roleplaying frustrating at best.
Misled into thinking melee was useful? Of course melee is useful. If you define "useful" as 'we shall never face a foe that we cannot engage in melee' then you would be mistaken.
If there's only an occasional flying enemy, then it is a player issue, not system issue.
If there are constant flying enemies, then I'd say it's a world coherency issue, which is a DM problem. If it's a world where melee is unusually weak, that should be made clear.
If another character can choose the same options and be mechanically identical then these things don't exactly scream individuality.
That's just a tautology. Of course if two players choose to make two characters the same way, they aren't likely to have much individuality. So what? Anyway, that's besides the point.
What I was talking about was your argument for why mechanics for theme and background are bad. Your argument seems to apply equally well to
all mechanics. As in:
Spells are bad because if the DM uses anti-magic fields, or monsters with high saves, the "crybaby" Wizards will complain instead of adapting.
Weapon attacks are bad because if the DM uses high AC monsters, the "crybaby" Fighters will complain instead of adapting.
AC is bad because if the DM uses high attack-bonus monsters, the "crybaby" Plate-wearers will complain instead of adapting.
Every single mechanic ever made is bad under your argument, because every single mechanic can be made less useful due to DM decisions, and there is always the possibility of some "crybaby" who complains instead of adapting.
I do not see any reason why mechanics from Themes and Backgrounds should be considered distinct from any other mechanics. So unless you have an argument for why they
are, or you believe that all mechanics are bad, your argument strikes me as rather unsound.
Being actually unique comes from the player, always has, always will.
Of course. And the more tools the player has to express the uniqueness of their character, through mechanics, the better.
But I'm firmly in the school of thought that
mechanics matter. If a situation resolves purely through the use of well-defined mechanics, used by the players how they saw fit, that is the pinnacle of a good, well-roleplayed outcome. The more DM fiat creeps in, the less the mechanics determined the outcome, the less I feel like I'm actually "roleplaying", and the more I feel like I'm playing the game of "guess how the DM will react".
So taken from that perspective, sound character mechanics are absolutely essential to me, for good roleplaying of those characters to be possible.