Deliberate IMO.
A lot of these less desirable bar areas (e.g. Soi 6 Pattaya) are not only an ebarrassment to the fake puritans in power, they are also on prime real estate.
So if they can drive them out they get to pretend they have cleaned up the image of Thailand (they won't have) and their cronies/relatives can pick up some cheap real estate for another mall, theme park, condo etc. Two birds, one stone.
It's a bad idea, because 'quality' tourists won't suddenly want to come just because the bars are gone. There will still be the broken pavements, hanging wires, soi dogs, taxi thugs, poor air quality, corrupt cops, flooding, sewage etc. so they will drive out the sex tourists and not much will replace them. Fortunately for them, they have such phenomenal wealth that the fate of the average Thai doesn't really matter to them as long as they get even richer.