So that people don't just reach out for it thinking it's the standard best model I guess. Opus is still, IMHO, the best intelligence per dollar, token, and speed.

Because it's a bad release and not even worth using over Opus 5.5.

The improvement is marginal, it makes the same exact errors as Opus, but slower and much more expensive.

From what I saw, it has slightly better taste in some 3D mechanics, but mostly doesn't even bring discernible visual improvement.