I am very anti-ganking, but I am also very much in the pro-"get folks back into open" camp, so I feel like I hover between two groups here.
I don't think we should do anything to restrict solo or PGs; no one should have their gameplay style hindered if they are used to playing that way. Many people just want to play alone, and that is perfectly fine.
What I DO think we should do is incentivize Open. As it stands, Open has only an additional con with no additional pros to it. If I log into open, I get all the same benefits I would have in solo or a PG, but I also get to have the random chance, however likely, that someone will pop my ship like a balloon and I'll lose everything I've worked for over the past few hours. So of course my obvious choice if I'm doing anything time intensive is to NOT do this in Open.
How do you fix that? Make Open worth it. Give me a reason to say "well, maybe it would be more beneficial to do this in open". Whether its buffing open's mission rewards for engineering mats or having mining have better returns, etc etc. Whatever the choice is- give me a reason to say "the risk is worth the reward". Because right now there is no reward, only additional risk, and I just don't see why folks would choose that if they are already used to playing in another mode.
Ultimately, Open needs to be given some purpose to its existence beyond PvP, or its only draw will be PvP. Which is fine, but since there are a lot of other things to do in the game that are not PvP based and would ultimately be harmed by unexpected PvP more than helped, that means that folks will have little incentive to bring their other tasks into Open.
IMO, incentivizing Open would be a boon to this game. Sandbox games thrive on either intensive and continuing story (which ED kind of lacks), on tools to shape the universe (which ED kind of lacks), or upon player interaction. We don't really have much of the first two, so capitalizing on the third should be our focus. Seeing and interacting with other CMDRs will help make the universe feel more alive, but we really need more reasons for folks to do that if some of those interactions can be unsolicited and unwanted PKs at very inopportune times.