One problem with the mining (or "airdrop") with a phone is about the minimum coin for trading on exchanges. You may not be able to trade ETN with less then $5-$6 (there is transaction fees to send the coins). So people may have to mine it maybe for 6 months before they can sell it. Also they need an enough powerful smartphone, else they are going to wait a lot more.
But if one ETN gets more valuable, it can be good to mine some in case of a price increase.