Dropped kerbs do take up slightly more room. And there's the extra danger of having an irate bald man rushing out and threatening to kill you because you've got a quarter of a tyre over his precious dropped kerb.. true story. The main thing is that they look totally completely rubbish - to the point that they can even have an adverse effect on that all-important house value and desirability. So I think the majority of kerbs were dropped by the previous wave of 'new' residents, at a time when being able to park your car in clear sight - two feet from your front room sofa - was, for some reason, considered a real boon. Many 'new' residents would rather convert them back, I'm sure. Some are doing so already, round our neck. If you go far enough back, 'new' residents didn't even have cars so it wasn't a problem.