With my suggestions, it would allow piracy. You can take a cargo hold to 0% and it will loose all the cargo. You can take out the drives. You can disable their weapons. But unless they strike back, you cannot destroy them outright.
If your ship has no drives, sensors or FSD integrity left, and the power plant, hull and life support are at 5%, and all your cargo has been lost, then not having to pay the rebuy does not really save you very much. Your repair bill is going to be a significant proportion of the rebuy anyway, you're down however much you spent on the cargo (or due a mission-related fine of even larger size), and you still have to get back to the station in a nearly-dead ship without running into any NPCs, planets, etc. who aren't limited in the damage they can cause you.
(A beginner might not even realise that they can reboot/repair to get out of that situation. And a real beginner in their Freewinder has zero rebuy anyway so saving them paying that doesn't really help)
If we consider the bigger ships, a Type-9 has a rebuy of 6 million credits, but can easily carry cargo worth 15-30 million.
On the smaller side, a Type-6 has a rebuy of just 200,000 credits or so in a "pure freighter" style of fit, but can carry 2-4 million credits worth of cargo.
Are there really that many people for whom the problem is "ship destruction" specifically rather than "losing a fight at a cost of millions of credits and time" that the difference really matters? (People with a bunch of exploration data, sure. But they already have ways to avoid PvP loss of that data - in Open - if they think that's a risk)
I would be curious the number of players in PG or Solo vs. the number in Open.
Frontier haven't said for a while, but the last time they did, the majority of players played in Open [1]. Nothing has significantly changed in any direction since they said that to affect proportions, so it's probably still true; anecdotally comparing the number of players I see in systems with the station traffic reports is still consistent with well over half of players being in Open.
As always the best way for Frontier to get more players into Open is to ignore people like you who would play Open if some very specific changes were made, and indeed to ignore the modes issue entirely, and just make changes which attract more players to the game in total. There are likely about twice as many players in Open now as there were a year ago, because Frontier has attracted more players to the game - which based on Frontier's statement means that there are probably more players in Open now (well, maybe not right now, it's a weekday morning - at peak times on a weekend, then) than there were total people in game a year ago [2].
Compared with that sort of effect, adjusting things on the margins to maybe get a few percent of players to select Open more often than they select Solo is irrelevant.
[1] There are also a lot of people who switch modes depending on what they're doing, of course. I mostly play in Open, I'll switch to PG if there's an event in a PG I want to attend, I'll switch to Solo if other players are being annoying (this generally means "pad hogging" rather than "shooting at me", in practice) or if I've got something I want to test out and even a friendly player might get in the way a bit, or if I want to take a high-res screenshot. So "the majority of players are in Open" does not mean "the majority of players in Deciat are in Open" or "the majority of players
solely play Open and no other modes"
[2] Of course, other consequences of those changes mean that there's now three times the inhabited system count, about twenty times the Powerplay surface area, etc. so the chances of meeting another player in any particular system have probably gone down.
). 
