[magduf]

24 bits gives you more headroom to work with, making mastering easier. It also quells any concerns about 16 bits being insufficient. As for "waste of space", the simple fact is that we don't have a shortage of space when you're talking about audio files. Hard drives are routinely over 1TB now. Remember, the person you responded to proposed offering the 24-bit version as an optional "audiophile" version of a track, not the default offering. It's not like everyone will want to stream the top-quality version for listening on earbuds.

[sjwright]

You’re correct that the file size of audio stopped being relevant many years ago. In a world of Netflix 4K streaming, even the most inefficient audio formats don’t move the needle.

(If it did matter, which it doesn’t, it occurs to me that you could even create a 24 bit file that only contains 18 significant bits [dithered to 18 bits then padded to 24] in such a way that the space was reclaimed by ALAC or FLAC encoding.)