Until FD actually does something about it, it's all up to you.
The problem is there's very little FD
can do about it at this point.
The game simply isn't one thing or the other. It was built that way, and it's not going to resolve now. It wants to cater to (among others, but on a spectrum between) PVP player-killers and solo-minded players like me ('carebears', if you insist) who don't enjoy or want player-combat interactions.
And it wants them, ideally, all in the same, open game. But that won't work, as we've seen right from the start: the two play styles are incompatible if you want both camps to enjoy the game.
To make what we have now work, the only thing we - the entire playerbase - can do is just
accept how things work. That means PVP fans accept that people can drop into and out of Solo/Group when they please and that people in Solo/Group can affect the Open mode background simulation. And it means that carebears (again, like me) accept that going into Open mode means people can blast you for laughs with no consequences. Acceptance of these things, and all the other little mode-related quibbles the forums are full of, means the forums should empty of these complaints. We've all heard them before, there's nothing to see here, move along. Just play the game, warts and all, and enjoy it the best way you can. Sure, Frontier can try to implement more crime-and-punishment mechanics, and people will subvert or exploit them because gamers, and somebody somewhere will always complain about how the mechanics don't do one thing or another properly.
Which isn't to say Frontier shouldn't try, or that Sandro is wrong to ask (although I do wonder how we've got this far in before this question's being asked). Just that my hopes aren't high for a perfect solution. But lacking that hypothetical perfect solution, if we can't simply agree to accept what we've got, I only see three permanent answers:
1) Isolate. Let the PVE players play in a solo or group mode that doesn't influence and isn't influenced by open at all.
2)
Extreme Isolation. Rewrite ED, and release the offline version Frontier said they'd release if they ever had to take the servers down. (Balance the price: enough to pay for the extra work; little enough to account for the lack of developing, hand-crafted content.)
2) Frontier Choose a Mode. Pick one or the other play style to support and support it exclusively.
I can't see that any of these would be ideal: they're either going to upset some players or cost Frontier more work. But ED has attracted incompatible player bases by trying to be all things to all people, and these are the only ways I can see a resolution. Anything else will just be sticking plaster.