Even if Rogues get an ability, the same issue applies. Balance has nothing to do with strength, and running across a tight rope is an act of balance. And yet, with what you are declaring the strongman with his 18 str and 8 dex is going to be far superior at running over a tight wire than the gymnast with the 16 dex and 10 str.
I get you want to make athletics somehow more, but the only overlap between athletics and acrobatics is climbing, and climbing usually shouldn't even involve a check in the first place. So I don't see any reason to combine the two skills.