I agree, I just find the cost a little skewed across the classes.
I always wondered why, if the game was focused on three tiers, that classes weren't necessarily built to support it. It bugged me when when I was looking at the 5e playtest documents. Why not give each class a class ability choice at each third level on one tier. That way, a class isn't making choices between combat feats and non-combat feats, but between various options in each tier. (Not that I'm convinced of the tier system, but it just seemed odd).
We could also build on this. There's no reason every class needs to be the same. What if every L1 character (not 1st level in the class, L1 character, like "every L1 character gets a Feat") got a combat, exploration and social ability. Perhaps these could be from lists dictated by race, rather than by class. Then, as they gain levels, their class determines what they get, perhaps
Fighter
Level 1 - Choice of Combat Feats
Level 2 - Choice of Exploration Feats
Level 3 - Choice of Combat Feats
Level 4 - Choice of Social Feats
Rinse and repeat
Wizard
Level 1 - Choice of Exploration Spells
Level 2 - Choice of Combat Spells
Level 3 - Choice of Exploration Spells
Level 4 - Choice of Social Spells
Rinse and repeat
Bard
Level 1 - Choice of Social Abilities
Level 2 - Choice of Exploration Abilities
Level 3 - Choice of Social Abilities
Level 4 - Choice of Combat Abilities
Rinse and repeat
I just thought it was odd that they put some much emphasis on the three tiers and then didn't bake them into the classes. Oh well.
No reason everyone has to have 2 in one category and one in the other two, either.