But you are talking about the status quo. Just because something is a certain way now and always has been is not a valid argument for why it should stay that way (especially because the whole point of this thread is to debate the merits and demerits of changing these mechanics).
I am just presenting the reasoning behind why I and many others who enjoy these features advocate for changing PP and BGS to open only in a civil and thoughtful manner.
Sensible suggestions aren't welcome here, you'll just get stawmanned by people who are desperate to maintain the status quo and are afraid of change (even though that change was suggested by FDEV themselves originally 5 or 6 years ago and obviously they still have it on their radar).
It all boils down to it feels awful fighting ghosts that you can never know.
This is the key point, Powerplay was designed with PvP very much in mind - but leaving it open to all modes with zero restrictions just makes the PvP players give up as everyone undermines enemy systems from private groups for tactical reasons. When I log in I'm not going to waste a whole evening looking for enemy players in my powers' territory if I know there's a high probability they will be in a private mode, it's just a poor use of time and you never find anyone.
Robert Maynard always says 'PvP isn't a requirement in the game' as his main argument against these points. But my argument is that to do certain activities, such as undermine an enemy player groups controlled system, it should be a requirement to run the risk of PvP because you are doing something deliberate against the interests of another group of players within the context of a PvP-associated system (I.E Powerplay - a system that depends on player activity, unlike the BGS which runs on its own).
The BGS is different because it was never really designed with PvP in mind at all, so we may as well give up trying to make anything open-only there. It will never happen.