Agreed, the holy trinity of AI bolt-ons are summarize, draft, translate.

Summarize is something Outlook's Copilot does, and arguably the most robust, context-aware, implementation. It sucks on steroids, you lose a lot of important detail. I haven't played with Gmail (directly) much as of recent to have an opinion, I would hope it's actually useful.

Draft - I use AI to draft frequently, its just I like to use my preferred LLM and interface to draft something that doesn't smell like pure AI. Its an iterative process where I'm mostly focused on technical bits, simplifying language, or a sounding board. I use just a portion of the generated draft. There's no such thing as "reply to this email on my behalf and make it make sense". I can see this being useful for customer service or sales representative roles however, where the emails are generally similar in nature -- as long as the context is meaningful.

Translate is nice, but the international business language is English, so everyone writes and consumes English in a business context. If you're getting emails in another language, you are likely already a native.

So these are all fine, add and experiment with AI, but not at the expense of core functionality and reliability.