[JetSpiegel]

At least on recent Android you can deny it. The UI doesn't support it and you need to resort to hacks such as https://whatsappwithoutcontact.com/

[daemin]

For WhatsApp in its initial incarnation I did not mind allowing it access to my contacts since the phone number was the way it identified people and since it was universal.

With these upcoming incarnations I'm not sure I want to use it, and I'll be looking for a simple IM application which just charges a simple fee for service.