Stickers are important for people like my sister and wife, who are put off if the messaging app doesn't support them. I wouldn't knock their importance, but yes, good syncing should come first.
My 6 year old son just discovered the augmented-reality tricks in the LINE app (adding a mustache, hair, glasses, sound effects etc). He got my mother (68) to install it and now they use it pretty much for all their video conversations. This replaced FaceTime, despite FaceTime having better sound and picture quality (edit: and even some effects).
He's in the age (and COVID-19 environment) where he starts speaking to cousins and friends online. So I imagine LINE spreading pretty quickly in similar circles based on those features alone. That's the stuff that drives adoption, as silly as it might be.
That said, yes, the plumbing needs to be in working order, or no silly feature can cover over the leaks (or smell, if we're going with the metaphor).
Favoring mustaches over security is always the choice you can make. I don't care about adoption unless it falls below levels to make signal worth developing.
> Favoring mustaches over security is always the choice you can make
Unfortunately not. If most of my friends and family favour mustaches and effects (which seems to be the case, I would imagine as a general rule), and I favour security (the minority, as a general rule?), then I won't be able to talk to them securely.
If they don't want to talk securely to you, then they don't want to, why do you want to force them to? They will spill secrets to other people all the time, using Signal or not. They will talk to other people about things you thought was a secret between you. They don't patch their computer. They use trivial passwords to their computer, they reuse passwords on all websites, they don't encrypt their drives or their Micro-SD on their mobile phones. Why should they care about things you want them to care about? They won't.
I use WhatsApp to people who don't care about security, and I can only be contacted by Signal for business stuff.
Seriously... I do not understand how they keep investing in this gold-plating when the plumbing keeps getting clogged up.