Comment by dont__panic

One of:

- we don't have the dev resources to keep SMS/MMS working

- with RCS becoming more common and no Google API for RCS, we don't have the ability to fully replace Google Messages any more

- since we can't support SMS/MMS on iOS, we decided to kill the feature for Android users for the sake of maintenance

They shouldn't pull punches and pretend that this feature removal is for the "protection" of users who accidentally send SMS instead of Signal messages. That's a strawman, anyway -- if a user manages to send SMS in the Signal app, it's because the person they're trying to communicate with doesn't have Signal installed... so there inherently isn't a secure communication path. Users who pay per SMS should disable it in the app settings, and you can easily add a popup the first time you send an SMS/the first time you open the app to make that clear.

This is 50% Signal trying to streamline development, 50% Google's push for RCS (and their lack of APIs to build alternative RCS apps on Android). They should be honest about that instead of making up nonsense about misguided users getting confused.