Solo (and private groups) players constitutes the vast majority of players. Ganking is but one of the MANY reasons people choose to not play in Open. The general lack of incentive to play in Open unless you are doing PvP (which most players don't) come basically from a "higher risk, same rewards" situation.
There has ALWAYS been talks about how to make Open better, and it boils down to this : offer something in Open that you can't do in private/solo. When PowerPlay come about, it was proposed that you shouldn't be able to contribute to Powerplay while in Private/Solo, for example. But sadly it never came to pass.
Speaking for myself (there may be others as well), there is nothing that can be done to Open to 'entice' me to become a flying target for other players. I just don't need or want other players and their antics screwing up my game. Period.