Banning it, will, just like anything, increase the demand for an illegal trade, and the prices will shhot up.
Here in the UK, you are likely to get away with it for a long time without getting caught, but I feel it should be made legal in certain quantities, such as no more than an ounce (usually about £45 worth), for home and personal use only.
Maybe the Dutch ban will stop tourists going there just to smoke, but then those people who did go over there for that, are just going to do it in their own country now, so it's gonna increase the use of it in other countries.