> Why not use a lossless codec if you care about quality?

(1) Lossy codecs are transparent at half the file size (or less) of FLAC/ALAC.

(2) AAC (strictly, AAC-LC) is universal, where FLAC and Opus are not yet there.

You can care about quality to the extent that a lossy codec allows. Lossless is not always necessary or wanted. This is like saying “why care about transcoding quality when you can keep the video as is?”. There’s a myriad of use cases and preferences at play here.

Because almost all people cannot hear the difference between a high quality lossy codec versus lossless in a double blind test. They think they do, but they don't.

There are a ton of older, but still perfectly usable devices that support AAC well but not Opus.