Airdrops are meant to gain traders of their altcoins, to encourage someone to register to their website, free advertisement to their platform by means of retweeting or sharing on social medias, to gain thousands of supporters or to enlarge their social community on slack, discord or telegram, etc. Actually, that airdrop is an eye catcher to cryptocurrency's freelancers which as known as bounty hunters.
Yes, correct. Airdrop is essential for a project to distribute their tokens to people to gain popularity and price volume. Its necessary since they cant just rely on selling their tokens to everyone who doesnt even recognize their project the first with.