I personally wouldn't like to see new ranks introduced as I am perfectly content with my current rank and don't need this feeling of having to farm something endlessly in order to have fun on the forum. Imho, people take this forum way too seriously and new higher ranks would only make things worse in that regard.
Of course, I would never have expected it either. I think 8 rank so far is enough after the merit system was introduced, but if the merit system is not required for rank up then adding a new rank is not a problem. I'm assuming hundreds of thousands of users are still very difficult to rank up to Legendary due to lack of knowledge, so let's just say that the few users who managed to get 10K merit more are dedicated users on this forum. So if some of these users are given special badge for their contributions, then I think it's better than adding new rank for users.
For every user who made it to 10K merit, congratulations on your success. I hope more users follow you in the near future.