IMO I think that alot of people make a big deal out of being gay and the public reacts negatively because they view us as outsiders and on the fringe... namely because there are several individuals out there that do want us to be outside and separate from heterosexuals.
As Hillie said, every group has a negative identity they must overcome...including ours. ...of course, we still don't have the same freedoms as heterosexuals, so we're still fighting the good fight.... and that makes us unpopular. Any group that comes in and wants to change the status quo is always unpopular.
....so, I'm not so certain it's so much as we're viewed as sexual predators per se, but more along the lines of people want to find reasons to not like us for trying to change the stats quo. ...and if those people can find a justifiable reason, then they don't have to question why they don't like that particular group.