For Byteball case, airdrop is just one way of getting the coins out to users without doing the ICO (Byteball has not done the ICO).
Since Byteball is built on directed acyclic graph (not blockchain), there is no proof of work and mining, so they can't distribute the coins that way either. Well, only exception is now the other airdrop to World Community Grid users, where the it's being airdropped based on how much users help with research.
And yes, awareness too, but it's not random airdrop to random adresses, users need to request the airdrop by authenticating themselves.
Another added bonus by attesting your Steem user is that you get your personal address in steem/username format, so other users don't have to remember your long cryptic address, but can send you Bytes directly to your Steem name.