You're right in saying that there's little point trying to define a PC in strategy games. That's not what they're about.
It sounds like the biggest issue here is the limitations of software. No software can provide entirely freeform character design, unlike pen & paper games. How much control does a computer algorithm have to apply before you no longer have a PC? In Divine Divinity, when I click on a distant location in the sewers my character does not walk in a straight line. He determines a route that will get him there as quickly as possible, as determined by an algorithm. So am I instructing an NPC? I think we need to accept that software can provide only so much and do the make the best we can of it. For many years to come we will continue to be plagued by selectable speech options and character control limited by the number of buttons on our mice. I don't care. I think it's fun!
I still don't understand why you cannot control a party of PCs and why only one of them can be a PC at a time. In turn based games, you lose no control over your party because your inactive party members couldn't be doing anything anyway.
