I can't see what Bluetooth would give to the iPodtouch, but why not, the more the merrier, right?
Just say the touch did have bluetooth..Would it work in the way of the Zune in which you can only listen to songs so many times and then you have to purchase them from the iTunes store? And would it allow for transfer of things such as photo's?
Bluetooth would rock.
BT headphones - cut the wires.
BT connection to my non-Apple mobile phone so I can take calls whilst listening to my Touch.
BT GPS so when I get my google maps when I have wifi or if I can download regions.
BT so my future Apple watch can show me my iCal alarms, be remote controlled etc
BT so I can use it as a Mac remote.