What for. The cryptographic identities are just fine and don't need another layer. We can pass them around instead of DNS names. I can print a QR code on my business card.

SimpleX needs to owe up to using IDs and advertise the fact as a Good Thing (tm). 

 It's optional. Some people may find use of them, I see this especially benefitial for businesses 

 You can create an address, its a long term way of contact and you can print your QR code