Which type of privacy breach is more likely to have tangible and direct negative effects on an average user's life - a nation state storing their communications in a database, Facebook graphing their contacts and using them for friend recommendations, or their friends/family/boss/acquaintances being sent random private photos from their phone and audio of private conversations they have in their home, without them knowing?
One of the main worries with companies having access to your unencrypted private data is that no matter how careful they are with it, it can still end up in the wrong hands. Signal is directly sending your data into the wrong hands.