Well for your second point, read my post. 5C hiding in Solo and PG are the bane of Powerplay.
I did read your post...then I wrote point 2.

The notion of people in Solo...being "invisible" to those in Open is a redundant issue. That's the nature of Solo and Open, that's how they were designed and will continue to be, it's core functionality of the game. To extend that notion out into the sentence "It's unfair because when I am in Open, I can't get at you if you're in Solo", is not just redundant, it's kind of funny. That's why they are in Solo, because they don't want to be bothered by you. That's why you are in Open, because you are trying to find people to bother. I congratulate you both on your choices.
Now, here's the crux of it. All that, was made complex...because some muppet designed a feature called Powerplay. Not only that, they beta tested it and the thing which beggars belief, implemented it into the game. I've given up trying to understand why that happened, just know that it did.
So Solo ain't gonna change...Open ain't gonna change....ever. The only rational conclusion is that Powerplay is not fit-for-purpose by design, has never been and if it's going to satiate the needs of both parties in the debate as outlined above, requires serious tweaking, if not setting fire to. This "solution" of making the existing Powerplay Open only as applied to the argument above, is not only very funny, it's somewhat derisible. There are many other methods through which those wanting PvP encounters can be satiated.
Explore those, not this. Unfortunately, we need someone who knows what they are doing to design it. Or if they are already in Cambridge...let them.
IAnd its a fairly decent question:" Why do you feel you should be able to attack the systems of other players, while simultaneously believing it is unfair for those players you are actively working against to try and shoot you for it?"
It's a very good question. However, it has a very simple answer. "Because that's the game we have". Solo/Group/Open are synonymous with each other, and together present the capability of the entire game as it is currently presented. Your question is a good one
through your lens. At this point in time, many people looking and playing the game through many different lenses are now formulating equally good questions. "Why do you think it's fair to pick on me as an inferior target if you claim you just want PvP?", "Why not design PvP clusters into the game so PvP'ers can find a good fight, in a timely manner...without relying on existing features"?, "Why not just play the game by the rules we currently have as they are the same for everyone and there is already something for everyone in game"? are just three of them, equally valid.
Thus, if you are going to assume ED will continue to be "equal across all modes", or conducive to "blazing your own trail"...the suggestion of Open Only Powerplay is a non starter as even though you make a great point, in the framework of the game, it is redundant.
However, if you really, really think Open only Powerplay is a necessity, then continue to lobby FD. they'll implement it, and then we'll have two games.
Whatever they call the new game as a result of the implementation will be up to them, and those in favour of Open Only Powerplay will play it.
Powerplay could be a fun feature for players interested in a competitive feature, rather than the senseless grindfest it currently is. heck, you yourself have gone on and on about how terribly stupid PP currently is and why noone ever plays it. And now they want to change it suddenly it should stay this way?
I'm not convinced it's mutually exclusive. I agree with you it needs changing, I'm just saying the proposed method of doing that is substandard in approach. Assuming a repeatable approach is in place.