Snerdguy speaks a lot of sense! I'd add that, as well as the practical reasons under those conditions, I'm sure there was psychological element - that urge that most human groups have (especially if they feel outnumbered or threatened) to define themselves as similar to each other but different from the other groups around.
I was circumcised as a baby, and very much wish i hadn't been - as well as wishing I had a nice uncut cock, there is that pychological effect (though I wouldn't call it 'traumatic' for me - that would be exaggerating).
But I don't think we should force our views on those Jews or Muslims for whom it is a deeply-held part of their religion and identity - maybe the solution is to require any parents who want their child to be circumcised to get a certiciate signed by them and their rabbi, imam, or doctor to say that it is essential for religious or medical reasons?
Incidentally, not all Jews regard it as essential - some liberal Jews do not see it as necessary. And occasionally there are good medical reasons - for example if the foreskin is painfully tight.