... told me just to write down famous temples and attractions for each day ...
Oh, you had to write it down for every single day? Crazy, isn't it? If I travel, at some days I just do nothing special and only relax. :)
... they told us we need to keep that form and give it back when it's time to take the plane for our country.
It's the exact same when you go to Thailand.
so that's a thing in all asian countries i suppose ( maybe in every country that need a visa?)
imagine to stay let's say for a month and you have this sticker in your wallet and someone steals it :P you are doomed. there are so many ways this sticker may end up lost :P
No, in Malaysia and Indonesia that wasn't required.