My issue is that people who have no experience or interest in powerplay or pvp whatsoever end up dictating how powerplay should be.
Ah! Ok. I have experience with PP. I played it a bit when it was launched. I also have an interest in seeing it improved, because as it stands, well, i think we can agree, its a bit pants. However, we can disagree on how it should be improved. Just flipping a switch to make it open only is not a solution because there are many problems with PP. Open Only could be a part of a bigger change to make it more interesting and engaging for players. As it stands, just flipping the switch i think would cause PP to hemmorage players. There needs to be something to entice people to play. Sandro made a number of other proposals that would help in addition to Open Only. If you are not familiar with those other proposals, then i suggest you check them out. So, any chance to improve PP is going to take quite a bit of work.
As for PvP, i don't have much interest in it. I've done a bit of PvP, i've been associated with a couple of PvP groups and helped promote them. I have nothing against PvP per se, and in the right environment and conditions, i'm fine with taking part (eg: CQC, duels, or other PvP focused games). Its worth remembering that PP as it stands is very much a PvE activity and a change to Open Only or the other changes Sandro proposed won't change that. Therefore the opinions of those who want to play the mechanics of PP via PvE should certainly be taken into consideration. Possibly much more so than those who want to use PP as an opportunity for PvP.
If you think only PvPers should have a say in PP, then how about the devs remove all PvE elements from PP and make it a pure PvP activity?