That already happens. A lot. I earn all of my PP merits through combat. In Open. I am there, farming, fighting, chasing PP enemies when I encounter them, hoping they don't drop in with a full wing - in which case I would very likely concede the field at that point, and do my best to escape. Which leads to..
Well, if I have been smacking your sides NPCs, gathering merits as I go, and your wing drops in, then the micro contest immediately becomes, can I escape with those merits before your wing dusts me. That sounds like a fantastic, and much more realistic contest than... Presto! We're here, now you can't leave because the magic invisible thunderdome has been empowered! You immediately have a small victory - stopping me collecting more merits, we both have a chance at a second victory - the merits I'm carrying, and the macro contest of overall PP merits carries on in the background. Sounds like the present system is pretty damn good. Now before you cry off about how easy it is to hi-wake away, well then start exercising those existing options! Equip your ships with G5 fast scan wake scanners and win that micro-contest by actually chasing me from system to system. Unless, of course, true PvPers only fit combat gear then campaign for the game to be changed to suit their builds?
Oh. So what you're saying is... Open Only isn't good enough, so even if OO were to ever become a reality, that wouldn't be good enough - every means of avoiding PvP combat must be eradicated and all interaction shall be forced cage matches. Boring.