Cannabis flavour vapes are available and I'd expect vapes containing THC would become available if legal.
Drugs of all sorts tend to be consumed more widely when they're more socially and legally accepted. In fact the rise of vaping compared to the fall in smoking is a good example, as is the fall in smoking in some countries compared to the continued rise in others where it's less restricted. However, we have prohibition-era USA as an illustration of what can happen when ill-thought out laws collide with huge commercial interests and thousands of years of habit. Cannabis probably isn't at that point yet but it might be soon.
As for the cool factor, if that was purely down to legality, we'd all have been shooting up behind the bike sheds instead of smoking crafty Woodbines.
And as for driving, lately I've noticed fewer nitrous cannisters all over the roads outside the clubs of Stokes Croft. I don't know what has replaced it in clubbers' affections, but whatever it is, it doesn't come in metal or glass. However, last Sunday I noticed a lot of nitrous cannisters on the lanes outside Gloucester, miles from any club. Could be the village youths are meeting up in the fields to sniff it, could be they're driving back from a night out in Gloucester, but either way, I bet it involves driving. I'm not sure how much that affects driving compared to cannabis, but then there are certain places where every other car window wafts a herbal aroma as it is.