Yes it's only small rewards but if it were much bigger rewards it wouldn't be good for the projects as there would be better marketing alternatives. Also don't forget that it's so easy to sign up to airdrops that you really shouldn't receive that much.
I really do not see any point in airdrops but really though, who cares since it is free money anyway and you would not really have to do much most of the time. The thing with airdrop is that you will have to be ready to hold as long as you want to.
Some may end up doing great in the long run and some may not, but the idea is to have a huge community behind the coin. It is easy for a project to end up highly volatile in the long run, when very few people are holding the market.