Idk what situations BG3 actually uses Athletics/Acrobatics...
I am guessing that in BG3, Athletics is rolled against target AC for Shoves. Again, this is only a guess. The formulas for Shoves don't appear in the combat log (why?). It could be rolling melee attack against target AC, or Athletics against enemy Athletics, or ???
Acrobatics could be used for walking across icy surfaces. But I think BG3 probably uses Dex STs.
Athletics could be used for shoving down doors, but in BG3 (Waukeen's rest) a pure STR check is used.
Athletics could be used for jump distance, but it may in BG3 just be purely based on STR
Athletics should be used for climbing, but this is not implemented in BG3. Either you can climb a surface or you cannot.
So, yes, I agree with you that BG3 doesn't seem to use these skills a lot.