The mouth breathers of society still try to get as close as they can though.
I find that by being assertive about my position in the road helps with that. I dont mean riding in the middle of the road but if you give them a gap with inches to spare they'll take it. If the road or gap is narrow move out and you'll force them to overtake you properly 
Spot on advice

Back in the mid 90's the missus decided she wanted a bike licence and as it was her first time on 2 wheels I went out with her as her pillion just to see how she would get on. Although she had road experience (and confidence) in a car, she was over cautious on 2 wheels and this was obvious by her general demeanour and road position (almost riding in the kerb).
One day we were out and we had this f**ckwit BMW driver who was driving so close that I could almost step off the bike and straight on to his bonnet. We eventually came to a set of lights and I got off with the intention of telling him to back off a little as she was obviously a learner and he would never react in time if she had to do an emergency stop.
In typical BMW driver fashion the driver got a little chopsy and responded with "if the silly tart ain't confident enough she shouldn't be on the road". I instantly flipped (she may be daft, but nobody calls her a tart) and poked said BMW driver straight in the eye with a gloved forefinger before getting back on the bike and telling the missus to ride away.
I went for his eye for 2 reasons:
1. It's very painful (for the recipient) and also ensures I have enough time to make good my escape before they hit me back.
2. He obviously wasn't using his eyes at the time, so I figured the temporary loss of one wouldn't have an impact on him.
I also gave the missus the same advice as you regarding assertiveness on the road and once she started riding accordingly it became a much more enjoyable pastime for her.
Another thing I have also noticed is that the bigger the bike the less the likelihood of other drivers trying to take the piss, I can only guess that's a psychological thing going on.