I'd argue that no-one having access to my messages should be the default case. The fact that a government could potentially get access to all unencrypted telegram messages sent by everyone is pretty off-putting. If they want my signal messages they would have to hack my phone, or MITM me and face potential discovery since verification status is unknown to the server. And that would only get them access to messages sent from thereon.

I understand your argument about the marketing and UI blurring the definitions, but I disagree on the fundamental issue. My messages should be readable only to me and whomever I sent them to.