Except the "fitness" standard in question really didn't have anything to do with actual fitness, i.e. can the soldier function and do their job.
Can those with felony convictions function and do their jobs? Those without diplomas or GEDs? I'm sure we could make this list much longer.
Your statement merely demonstrates how society changes its mind (our minds) about who's fit and who's not. Yes, we can change our minds, but it is not always, uh, fitting.
For the record, I am fine with letting the military decide whether homosexuals can serve openly, or at all. If they think it will work, then whatever. I just hope the recent decision was the military's choice, and not something foisted on them by politicians (even politicians in uniform).