The idea of trading Bohm isn't addition by subtraction. It's that he has trade value and the Phils have needs. He's coming off a career year, and it isn't a given that he's overcome his defensive problems. I suspect he won't be a 3 WAR player next year.
That said, I wouldn't trade him unless we get better value at a position of need. I wouldn't object to Jonathan India being on the Phillies, but he is not really better than Bohm. Just a different skill set. If they trade Bohm, it should be to improve the team.