I've got mixed feelings about this.  We were living in Hoi An for about 6 months last year (out on the coast, not in the old town) and the town's complete inundation seemed unsustainable to me.  Trying to ram all those massive tour buses down the old lanes is just stupid.  They do enforce some pedestrian-only hours in the old town which makes a big difference.  

But I don't know how much thought goes to the impact of changes like this on the local economy.  The old town's economy is already pretty much Disneyfied: a monoculture of boutique stores and tailor shops and a lot of pressure on rents for local business owners.  As mentioned in this article, regulations like this probably only worsen the pressures on "local" businesses in favour of the bigger money.  

Change is needed in places like Hoi An but only after all the consequences, intended or unintended, have been considered. Or maybe they have been considered, and that's the whole point.