You can either make e2ee easy to use and enable it by default, or you can try to make people understand what they are doing to protect them from edge cases. Conversations does the former, while not making the latter impossible.

…the “edge case” that e2ee should protect from third parties such as an admin to read the messages. A new key could create a pop up window that informs the user. If user doesn’t care, there can be an option for “never show again”. Having a function that says “verify key”, should also be expected from an app that argues to have secure e2ee implementation.

as most people don’t really need strong e2ee anyways.

Most people don’t need any. It’s infosec larping what people do. And then software developers build software for LARPing.