The only reason it's free is so WhatsApp can make money at some point. If there are people who won't pay, ever, then there's less reason to keep them as users.

Not "no reason", however. I'm sure WhatsApp could find a way to monetise them, or just leverage them for network effect. WhatsApp is a lightweight replacement for text messages, not a full-blown social network. You pay a buck, you get free text messages, not unending trickery to overcome your privacy options. I have WhatsApp contacts worldwide, so even if some countries reduce their usage there's benefit in sticking with it. For $100 I'd stop using it. For $10, I'd think about it. $1 is a no-brainer, and I live in Africa.

Now I just wish they had a supported, paid-for API I could integrate with.