"Chat UI" can "feel" a bit thin from an eng/product when you initially think about, and that's something we've had to grapple with over time. As we've dug deeper, my worry about that has gone down over time.

For most people, the chat is the entrypoint to LLMs, and people are growing to expect more and more. So now it might be basic chat, web search, internal RAG, deep research, etc. Very soon, it will be more complex flows kicked off via this interface (e.g. cleaning up a Linear project). The same "chat UI" that is used for basic chat must (imo) support these flows to stay competitive.

On the engineering side, things like Deep Research are quite complex/open-ended, and there can be huge differences in quality between implementations (e.g. ChatGPTs vs Claude). Code interpreter as well (to do it securely) is quite a tricky task.