You can use WhatsApp to talk to people across the world, you bet your ass that nobody would be using it in Indonesia and Brazil if it costed one dollar, vastly diminishing its value.
If you want a free app that only part of users worldwide can afford there's already iMessage.
WhatsApp had payments (or a pilot) pre-acquisiton. At $1/year, it was an amazing value proposition even for those earning $1/day. IIRC, this was when WhatsApp had 3-500M users globally. Interestingly, they allowed people to pay the subscription on behalf of a contact, so the Indonesian expat in Australia could pay for friends and family in Indonesia, and the aervice could have reached a bullion users and 500M/year revenue with about 200 employees
Are you nuts?
Only web browser justifies that