I think that public timelines should be hidden by default, for many reasons.

- You will receive less abuse when the only people who see you have opted-in to seeing you.

- Public timelines are rarely good. The Fediverse tab is mostly low-quality content. The local timeline makes discoverability good, but we could also have discoverability other ways, like a profile directory, or through trending hashtags. Hell, maybe even a centralized "find friends via Twitter" thing. Eventually Groups will be the best way.

- It would make the Fediverse as a whole less neurotic, and the Federation Wars would probably die down a bit.

- People have already removed them. Librem.one, for example, and Gab's new frontend design. Twitter doesn't have a public timeline either, and it seems to be doing well.

The home tab would stay, but the others would be buried beneath some menus for those who really want to see them. I don't think I'll do this until there's better discoverability though.