Currently the motivation is mainly speed. For the really easy ones like "hey, how's it going?" or "sorry I didn't hear you, can you repeat?" you can easily send to Llama3 etc. Ofc you could do some clever caching or something, but training a custom router directly on the task to optimize the resultant performance metric doesn't require any manual engineering.

Still, I agree that routing in isolation is not thaaat useful in many LLM domains. I think the usefulness will increase when applying to multi-step agentic systems, and when combining with other optimizations such as end-to-end learning of the intermediate prompts (DSPy etc.)

Thanks again for diving deep, super helpful!