I'm not surprised at all. 3 out of 4 big message apps (Line, WhatsApp and Wechat) don't support full message sync, it's clearly not a showstopper for mass adoption. 99% of the people don't need it and it's hard to implement correctly. Not importing old messages could be a security feature.

Stickers on the other hand are something that does attract many casual users and has no security implications.

Payment features... I think it's a bad idea for many different reasons but it might attract many users if it's not too complex.