My question after reading all the comments here is, is there any alternative? or is there really a choice?

If I have to build a social networking site, say - FriendBook, what features would you like in it?

So is the case with WhatsApp.

Privacy, if not now, will be unsustainable part of business model later. Look at Apple Ping[0].

[0]https://en.wikipedia.org/wiki/ITunes_Ping