I don't really see the issue. Minimalism is a sliding scale.
Just because the design goal was for it to be more minimalist than a typical Android/iOS phone doesn't mean they have to go full-on "NO. It's only for phonecalls and maybe SMS!"
Playing music isn't particularly "maximalist", and WhatsApp certainly isn't (people in the US need to understand that WhatsApp is basically SMS for most of the world). Maybe maps is, but it's optional anyway so who cares.
This device looks very cool to me. But there's no way it won't cost an absolute fortune, which kills it IMO.
Even in USA nobody ever SMS me. Messenger and insta are primary with WhatsApp and signal sometimes being relevant and wechat for the Chinese community.
Unencrypted is not the thing that bothers me - after all, Telegram is so popular, so not like most people even care. What bothers me is that you still need to pay for each one! You have to edit the texts to fit into a tiny arbitrary character restriction or else you's be charged for a second message! Why is data do relatively cheap, but those messages are still overpriced?
Mobile plans as standard here (in the UK) offer SMS for free, can't remember when they used to routinely charge tbh. But I think I only text my dad as he's very old school, everyone else is Signal/WhatsApp/Telegram