For me this was why I formulated the 'roles for modes'- solo and PG generate what open moves. Each side has its job and risk attached in a logical way.True enough, but the question is, do the new rules improve the problem?
Right now, pvpers have a legitimate complaint('pvp doesn't matter'), and an intractable complaint('I can't pvp everyone'). Your solution, while making open powerplay more even with solo powerplay, would still not actually solve either problem.
The goal of rule changes is to solve - or at least mitigate - problems to the point where they can be ignored. I don't feel like your solution would serve that end, and may in fact generate new complaints('Powerplay missions are too hard').
Which is why I prefer a more targeted approach. Solve the legitimate complaint of pvp not mattering(via open-only server-hosted pvp areas), and ignore the intractable complaint entirely. Leave non-pvp activities alone, so anyone can participate. There will still be pvpers complaining that they can't kill everyone who doesn't choose to play in open, but they will at least have the salve of being able to do SOMETHING in open that does actually matter. And on the flipside, it creates a gateway to pvp, as fighting other players around your Power's stronghold megaships should give a significant advantage, making it easier to justify getting into the game.
I'd also say that the intractable "I can't PvP everyone" is an unrealistic expectation- in Powerplay its the potential for random encounters within a framework- in essence using the threat of other players as an obstacle to overcome. In the end its preventing the perfect from being the enemy of the good.
And as I stated here (I think) missions would start at the current mission difficulty and scale above- people can then either contribute in safety or risk it- after all we do have high threat level POIs (esp. Thargoids) and having room to develop into is giving advanced players something to chew on, even if its not quite like other players. Its all optional, across all modes and can be tweaked.
We know right now that PP NPC difficulty is nil- inside areas of activity they are cannon fodder (because they have to be) and outside they are weaker still- its why a lot of players complain PP is nothing more than cargo moving and that its the BGS aspect with all the missions and roles that provides the fun.