Manufacturers select idle speeds appropriate for starting, oiling, fueling, and lack of timing chain or valve train backlash. Run it lower if you want, just tell us what takes a shit after a while, so the next time this question comes up, we can be more specific!
People are always trying to slow the idle down on Road Stars to that lumpy, lopey, this piece of shit can barely run sound and I'll never understand why. I get that your XS can slow down significantly and not sound like that, but seriously, the idle point carries a number of factors.