Ok that's just simply untrue Irdegg, Many classes run 2-3 such primary abilities.
Just look at the druid, it's got full casting an animal companion, and wildshaping.
Ranger: Combat style, animal companion
Paladin: Smiting, Mount
Barbarian: Rage, great survivability
Rogue: Sneak attack, skill monkey, survivability
Furthermore I'm trying very hard to avoid the mistakes of the monk's unarmed progression here. The monk fell into the trap of suck now, be great later. I.e. their damage output compared to a similarly focused martial weapon using class was low until their base damage got bosted a few times at which point it became increasingly difficult for the weapon user to keep up.
Yes I want the natural weapons to be improved at higher levels but I like the idea of doing that with abilities instead of increasing base damage.
I'm working on some fear effects that I think should be the last major ability, and involves all the other abilities. I just really wish I could implement the skill use version, I'm just worried it'd be OP with all the cheap massive skill boosters.
So I'm thinking a more traditional type thing, Will save to avoid being shaken when X happens, increasing area and the number of triggers as level increases.