"They are bad for the environment, as they rely on cryptocurrencies that cause huge amounts of carbon emissions. They will continue to rely on these systems for security reasons (despite claims to the contrary about moving to other systems)."

Moot point. Some are already proof of Stake and ethereum will be switched to PoS.

Might as well say storing your photos on the internet is bad for the environment and doesn't provide any benefits.

There a plenty of reasons why NFTs can be bad but this ain't one that applies across the board.