I think the main concern is about the capacity to handle that many tourists. As the population increases and general prosperity increases, amount of tourists will correspondingly increase. There are not that many tourist spots for a given location and causes overrun. There need to be some throttling function. Probably increase the cost/tax, or reduce the visas. Or increase the ability to handle so many tourists. I don't know how this can be done. May be better infrastructure and new places of interests.