I doubt it would be a thing for relays. Nostr is meant to be a text protocol and I don’t think anyone wants to change that. I assume most protocol developers would prefer that non-text be stored in a different service and clients would just hide that from the user.
Discussion
This is just another red flag for regular users to avoid Nostr because of usability and fragementation
The XMPP model of a "separate" http upload service integrated might not be the worst thing. Along the lines of relays, you could probably specify your preferred HTTP upload location, and have a NIP for standaradizing marking an http upload as an attachment, that a client can render or not in their preferred way. That way relay operators can opt-in or -out. Although http upload for xmpp has become not-really-optional so maybe it is just a ratchet approach rather than all at once
why is it a red flag? text only keeps the relays running well