For me, as a predominately PvE player who flies in Open, there's a few parts to the issue.
Firstly, there's the stuff that Mobius SHOULDN'T be doing. Like Spying on PvP groups, harassing people out of game on sites such as LinkedIn and bringing ingame computer drama out into the real world, such as questioning a players ability to be a Nurse, because they PvP. Particularly when it and it's administration team try to paint themselves as holier than though and an innocent victim. It's a hypocrisy I really cannot stand.
Then, there's the issue that a lot of the Mobius advocates on this forum were among those who promoted combat logging, which is just cheating. As I've said countless times before, I can't stand cheating.
Thirdly, it's the thorny issue of indirect PvP (Powerplay/BGS wars). Before we get into the usual 'different timezones/platforms/connection issues' excuses being carted out, to sum it up succinctly, the deliberate thowing up of a player made wall to avoid reciprocity while kicking over another's sandcastle to me as a player, doesn't feel right and was a serious cause of toxicity for player groups (which I don't like to see, as its usually the strength of the player group communities that keep games like this alive) from the start and feels like an oversight by the Development team (one which they tried to partially plug with Powerplay, until every unshielded type 9 pilot started throwing their shoes at Sandro for suggesting 'open incentives' for it).
Finally, the odd need for Mobius advocates to declare any good story to come out of open or just a general discussion on open, as being written by a 'SDC/griefer/CODE shill trying to lure people into their killing grounds' and that 'they don't care, open is dead' while filling those threads up with ridiculous off-topic nonsense.