As per the things we are seeing from the past the Airdrops are completely useless which we don't make money through these airdrops. Some times it is impossible for us to sell the coin which we get through Airdrops, so instead of wasting our precious time in Airdrops better concentrate on best bounty campaigns.
I think the way it is at the present it will become useless in coming time and nobody would be very keen to get those as those will be worthless and as good as not having it. That is the reason people are shifting to buying the better coins where you can invest and get returns on it.