+3!!! I find this is the single most annoying "feature" of mattermost. To me it's a bug. If a channel is "public" let it be viewed/searched by any user without requiring them to "join" the channel first. Search should be a tool you can use to find channels you are interested in joining. It defeats the purpose if you can only search channels you've already joined.

That said, I think the main issue is not that you have to join a channel to view/search it, but that joining a channel spams all members of the channel with a join message. Does anyone care to be notified when someone joins a public channel? Our users certainly don't. The simplest solution to this would be a global setting to disable or hide join/leave messages for public channels, or a setting on each channel to disable/hide join/leave messages. I know there's a setting for each user to hide these messages but that doesn't prevent spamming most users who aren't even aware of this setting. It should be a global or channel setting. It still wouldn't solve the search issue, but it would be a good start.

That would be great !! +3

This feature would also solve an issue where people can not leave a channel: https://github.com/mattermost/platform/issues/6152

A functional description of how this could work is here: https://github.com/mattermost/platform/issues/6153

That would really be great. As public channels are "public" the messages are just spam.
I think RocketChat has a nice implementation of that where you can always view a public channel, but you can only write something if you join it.

I think it is also important to make public channels searchable by Google, so if some issue was discussed in the chat people outside of the chat will be able to find it

Any progress on this? This feature is superimportant!

Proposing new feature:
Add ability for admin to make certain channels PUBLIC.

By PUBLIC I mean, that anyone, without any account whatsoever can browse content of the channel by opening it via URL.

As discussed here:
https://forum.mattermost.org/t/mattermost-publicly-searchable-channels/914