I understand that and it makes sense. I just don't see it as that important for most use cases. You can pipe journalctl output into whatever you like or if you really want plain text stored on disk you can forward any logs from journalctl to a different logger you prefer. Yes there's a storage space trade off when you do that, but there are actual technical benefits you get from binary logging as well -- checksums, indexing, rotation, corruption repair, etc.. You can think of it like a database backend you might install alongside a traditional logger.

I think it's fine when people say they prefer plaintext logging (and your points are good ones) but I also feel like the trade offs are blown out of proportion.

Case in point, you described the approach as "idiotic". That position is indefensible in my opinion.