Hmm. I see what you're getting at, although I'd quibble that character advancement management and inventory management and combat tactics and so on are player abilities.

But if I understand you, the difference to you is that in an RPG it doesn't matter how good the player's physical abilities are -- reflexes, manual dexterity, etc. It only matters what decisions the player makes.

I still prefer to describe the ME series as a hybrid of shooters and RPGs, because they are no more pure action games than they are pure RPGs. However, I can see the validity of both "shooter with RPG elements" and "RPG with shooter elements."