Chatters endpoint is already on the Summer 2018 roadmap https://blog.twitch.tv/twitch-api-summer-2018-roadmap-update-6036065f0098
Some of what you suggest, such as showing Twitch staff, mods, active chatters etc… could already be implemented in client-side scripts/browser extensions.
My view is that the chatters list should always be as complete as possible (and I hope the new endpoint includes additional data that the current undocumented one lacks), and any filtering should be client side. While I don’t particularly like “lurk bots” especially when Twitch supports the “follow for follow” nonsense which inflates both chatter and follower numbers, I still think that those bots should be included in the chatters list and that they shouldn’t be filtered server-side, although filtering them client-side by default could help prevent those profiting from the follow for follow stuff.
Some things you’ve suggested, like email verification, could add overhead too so may want to be avoided. Really though we just have to wait and see for Twitch for release info on the chatters endpoint they’re working on and go from there.