Not sure I get you. BT has nothing to do with wifi. When you use NFC to transefer files between Nexus devices you are doing it via BT. There is no wifi involved in the process. On the other hand those cute Samsung commercials that used to show people quickly sharing files between devices in front of a bunch of people waiting on line for a new iPhone did use wifi direct as part of the process, but that was a Samsung feature not plain Android. Samsung's utility would use NFC to quickly turn on and off wifi direct on the 2 phones.
BT +HS which Samsung Implemented in their Android devices (since the OG Galaxy S) does have something to do with Wi-Fi in that it would do the Data Transfer using an 802 protocol instead of using BT EDR (after doing the pairing/handshaking over BT), which allowed it to achieve speeds 10x that of BT EDR.
Issue is, like most things, lots of phones don't have BT +HS implemented. Samsung has been the only OEM to consistently implement it, so you only get that between two Samsung devices.
Even without Wi-Fi Direct, 2 Galaxy S2 devices will still achieve probably 8-10x the BT transfer speeds than 2 Nexus devices (even 2 Nexus 5 devices).
Another benefit of that is the increase throughput when using the phone with a PC over BT. While most non-Samsung phones do not support BT +HS, a ton of PCs/Notebooks with BT chips in them actually do and I'm pretty sure most of Samsung's Wi-Fi Tablets do as well
For synching over BT or Tethering over BT, this has huge benefits there...
Without BT +HS, BT (or anything that uses BT for the transfer) isn't even worth using for any data of decent size. It's simply too slow. 200MB Video can take forever just to transfer. It's like downloading it over a 2mbps internet connection...
Google needs to make Android Beam use Wi-Fi ASAP. They should have done that when they opened it up to data transfers (instead of just links, contact data, etc.), IMO.
Facebook
Twitter
Instagram