What is the reason for which airdrop coins always want the ETH address When they can pay in ETH coins instead they should give directly btc coins of that appropriate value? Is that not possible for them or is there any advantages for them to pay in ETH rather than btc?
Bitcoin commissions are much higher for the sender, even if you send a small fraction of a cryptocurrency.
And the other main reason is because almost all airdoped cryptocurrencies are ERC20 tokens created on the Ethereum Platform. It's easier for them to use ETH addresses to send the airdrop.