I'm not saying that BTC is useless. I just think that there are better projects out there to be used for microtransactions.
Though Lightning is not quite there yet, there have been great wallets lately. Check out the Phoenix[1] wallet.
As for on-chain, I'm really not sure, but it makes sense for me to accept sort of "coffee transactions" that are worth $2-$4 without waiting for a confirmation, probably with just a minimum of 1 sat/byte fee just to make sure that the transaction actually goes through after a while. Because as far as I know, no one in the right mind would actually risk going to jail by attempting a doublespend just to save $2-$4.
[1] https://phoenix.acinq.co/
As for the Lightning network... Did you read this article saying that there is more Bitcoin on the Ethereum network (WBTC - wrapped BTC) than there is on the Lightning network? I think that Lightning network is far far far from being adopted.