I once had a Jewish girlfriend who actually claimed the procedure was necessary for hygienic reasons... as if it would be so difficult to spend an extra ten seconds cleaning one's self in the shower.

...do you mean now?

...or do you mean as a desert tribe miles away from a signifigant source of water, several thousand years ago?

The two are different questions. And when you walk 50 miles to the well, you don't waste enough for any 'shower' - let alone one that's 10 minutes longer.