Depends on where you live. You'd be a monster here if you didn't use WhatsApp :D
I will double check, but I think the setup and configuration is already complete for most people's phones, so no additional install needed.
edit: to clarify I mean I should join the opt-out side to help stop it from becoming socially unacceptable
It is perfectly possible not to use them (I don't), but it is not without downsides.
Either way, it's time to switch banks. And it's a good thing that you told me about it, as in Romania we also have ING and was considering then for my business account.