Luddite
Call me a Luddite if you like but I simply do not trust the pay by wave system.
There may well be safeguards, encryption, payment limits etc but the past is littered with such systems that ended up being compromised. At least with the current system the card has to be physically removed from the wallet in order to be compromised.
Fortunately, non of my current cards support this and as soon as I get one that does support it I will researching how to permanently disable it.