Originally Posted by gastrocnemius
their propensity to hook on trees...
I actually find the opposite to be true. When I'm in tight with some trees, I have often found the bar ends to be useful for guiding my bars around the tree rather than having the tree smack into my brake lever/hand. It may not be good form, but I sometimes use them as a sort of hand guard.
The other thing is that, occasionally, I have to take my bike on a semi-lengthy road ride through town (hey, it beats taking the bus). Raiyn's fanatical misgivings notwithstanding, the bar ends on my risers (which actually don't rise very much at all) are a great help is such cases.