90% of the options available to martials (especially fighters) are combat options. Fighters are fine in combat but take them out of it and they have few options outside of "get creative with your skills.."
Sure, but first a fighter has to get persuasion - not too hard, but it's not on their skill list. That means getting a race that can provide it or a background that can - which may not be optimal. And if the fighter "just" takes the skill they'll be pretty bad at it. Basically their role will be to assist the guy who's good in the party (to give them advantage). Assisting is all well and good, but, sometimes, you want to be the actual guy!
So to not be completely terrible at it (regardless of proficiency) they need to have at least an "ok" CHA since that's normally 3rd or 4th (or lower) on a fighters priorities they have to sacrifice something to get it up there.
Then you mentioned expertise - only way a fighter gets that is either through prodigy (assuming feats are allowed) which means variant human or 4th level - and fighters need their feats (and ASIs) A LOT more than casters, so that's a TRUE sacrifice. Or the fighter could multiclass (assuming that's allowed) but that's a whole different discussion.
Even the current option in Tasha's - take commanding presence to be able to add a superiority die to (some) charisma checks is a massive investment as fighters don't get all that many maneuvers (or dice for that matter as every use will impact their next potential combat).
I just don't see the harm in exploring some serious options to help in out of combat utility (such as giving fighters an out of combat dice pool and maneuvers).