with higher levels, magic items, spells, it's actually quite easy to achieve 95% hit-chance
If this frequent misses will go away before half the game, I could accept it. But I did not see what BG3 or DnD rule would help with higher levels ?
I understood that we will slowly increase proficiency, at 1 per 4 levels, and since I read that max level will be 10 it means proficiency will cap at ... 3? That is just one more point than now. Same with abilities, we get 2 more points at lvl 8, which translate to one more Ability Modifier point. That totals +2 to Attack Rolls.
On the other hand, I also understood that DnD rules call for increased AC with mob difficulty, it was from 13 to 19 AC IIRC, which is +6 AC ... and if that is across 20 lvl range and if I can assume +3 AC at lvl 10 compared to now, that totally annuls those +2 improvements and make missing even more often at lvl 10. Regarding spells, I looked at full list of spells on wiki, and unless those are only early access spells, only Bless affected directly attack without giving advantage.
In short, can I really expect less misses on higher levels?
Probably, yes. Let's say we will be level 10. In DnD, this often means your DM will pit your party against enemies with a CR of 8 - 10, maybe 11 if he likes his/her players to feel excited and fear for the life of your characters.
Or your DM will throw several monsters with a far lower CR at you.
As a suggestion the rule of thumb goes: party of 4 heroes (with lvl X) = 1 monster of CR X.
You could also say, for a party of 4 level 8 heroes, if they are attacked by 4 CR 2 monsters, it's also quite a worthy challenge.
When I look at monsters with CR 10, there are exactly 50 monsters (I can find in DnDBeyond).
If I filter these monsters by AC, then I get the following:
AC 21: 0
AC 20: 1
AC 19: 5
AC 18: 11
AC 17: 19
AC 16: 4
AC 15: 5
AC 14: 2
AC 13 or lower: 3
Let's go with AC 17 here.
I assume a fighter with STR 20 wielding a Greatsword +1 (with a generous GM maybe a +2).
Her boni are: +4 (proficiency bonus) + 5 (STR ability bonus) + 1 (item bonus): +10
So she needs to roll a 7 or higher (7 + 10 = 17 --> hit): 70% chance
She gets buffed by Bless: 75 - 90% chance
She gets advantage (by a spell, or something else): 91% chance
She gets Bless + advantage: 93,8 - 97,8% chance
so I think at level 10, it's reasonable to assume to have a hit chance of around 85% or more, especially when you think about Bless being a Level 1 spell (and don't ignore the bonus to saving throws! it's such a great spell!)
