PFA is fine for analysing 'passivity' if by that you mean likelihhod of caling as against bet/raising.
The liklihood of folding when bet at (or of not betting when checked to) can then be called 'weak-tight'.
The porblem is that when playing you use aggression to, say, check a string hand in the expectation of being bet back at.
Now there is some correlation between high PFA and this in practice, but there are also players who check/fold 90% of flops and bet/raise 10% and are therefore shown as highly 'aggressive'.
You can of course manually pull up the above stats for a given player in 15 seconds or so if you have the main PT window open but minmised. It's a case of the overlays needing to catch up with our needs.
The idea of some % stat showing the ratio bets/raises to say checks/folds would be nice think.
I'd would also like to know folded at river % for an opponent if I'm going to run a big river bluff (or indeed am value betting)