It literally works seamlessly though? Just converts to MMS and you don't notice outside the "liked BLABLABLA" sort of messages that trickle in without the imessage emoji system.

I don't think seamless integration with MMS is enough to outweigh being different/not having "the real thing" or the full experience in the eyes of a young teenager. This reads as the HN version of the "but we have iMessage at home" meme (I mean this humourously, not as snark).

Even that has been fixed by now in my chats with android friends. The only reason to display green bubbles anymore is to indicate lack of E2EE. But that will be coming to RCS interop soon as well.

In theory it's ok. In practice, MMS group chats are broken. It's not even an iPhone thing, as evident in Android-dominated areas still relying on WhatsApp instead.

Non-iMessage chats are also segregated by color, a visual affordance that identifies you as a member of the non-Apple outgroup. The other.

iMessage chats also include rich media that is either degraded in MMS (photos, videos unless you have RCS support) or just doesn't exist (like multiplayer games, invites, apple cash, etc).

This may not seem like a big deal to you, but if you remember what it's like to be a kid, you should get it. The smallest friction can be a reason to exclude someone socially.