Now that OnePlus unveiled its “2016 flagship killer,” people are starting to comment on what they would have wanted to see in this device, but has been omitted by the Chinese company.

One such feature is NFC (Near Field Communication) and is used for contactless payments, but also for sharing files between compatible devices.
Most high-end smartphones have it, not just flagship devices, but OnePlus 2 lacks NFC, and for good reason OnePlus says.
During OnePlus 2's VR launch event, the company announced there would be two versions of the phone available for purchase beginning August 11: 16GB (3GB RAM) and 64GB (4GB RAM).
None of these devices comes with NFC and the folks over at AndroidPolice have the answer as to why OnePlus did not include it in the first place.

OnePlus One users said NFC can be left out

According to OnePlus, “we heard from a lot of users of the One and saw most of our users weren't using NFC.” So, NFC has been cut out from the phone's specs configuration based on users feedback.
Obviously, there's no reason to believe that OnePlus' officials did not tell the truth, but there are still a significant number of customers living in markets where contactless payment services are very useful and they will definitely want to be able to use it.
Even if you don't use it much now, it's nice to know that you purchased a flagship smartphone and you have the option of using NFC at some point in the future.
OnePlus, on the other hand, probably wanted to cut the costs of their smartphone but a few bucks in order to offer customers only the features they use more often.
The lack of NFC is certainly not a deal breaker, but for a device that calls itself the “2016 flagship killer,” it would have been nice to have it.