In reply to mypyrex:
It is certainly a risk, but probably a minor one compared to the act of riding a motorbike in the first place! Helmet is most important, followed by gloves, then jacket and trousers. None of them are as important as riding sensibly and doing all you can to avoid accidents.
In this country, I always wear full gear because it is no inconvenience. In hot countries, I have occasionally just used gloves, and helmet, but it does feel wrong.
I once tried to resuscitate someone who had obviously come off his bike at very high speed (broken helmet, massive chest injuries etc) wearing light denim/ t-shirt. I was surprised at how limited the injuries to his skin were... On the other hand, I know someone who lost three fingers in a relatively low speed moped accident (no gloves).
A bit like helmet wearing/ soloing in climbing in my opinion. Take the risks you are happy with and don't complain if it goes wrong.