I don't think it would too much of a problem, but I would not recommend it. I think having good footwear which would provide protection of your feet would be better, as a lot of areas do not have paved streets, are not the cleanest, and there can be debris. Even temples and landmarks have broken stone, which can cause real injuries if you stub your toes or trip up on them. I have seen tourists have to get medical attention because they did not have appropriate footwear, and that potential can be a real downer on a fun trip. I can empathize with wanting the openness and comfort of sandals, but you might want to look into some airy walking shoes of something that can breathe but still provide protection.