1. For you to actually receive the airdrop the project has to go through a successful ICO and funding stage. - In many cases they fail, so you get nothing.
Most airdrops didn't have an ICO.
They want to build a community with no funding. It was a success in the past at some of the cases but unfortunately the hype is not the same as before.
2. Even if you get a few tokens you have to wait for the project to list on a decent exchange, or sell it on dex like EtherDelta, well below their value. Even after they list usually a huge dump occurs so even if you get a few $ worth of tokens, their market value will drop 70-90% if you don't sell them in the first day of listing.
It is not really worth your time.
Also in the past, a simple giving of an ETH address won't really consumed time. And the best part, you can expect a decent return even selling on DEX. No need to wait for listing on big exchange.
Today, lots of tasks needed just to be part of airdrop and in the end not worth the effort. Yes totally a waste of time.
But OP might need experience. Let OP see how's the airdrop situation today to truly understand what we are saying here. Additional knowledge for OP in the end.