This isn't an NEX thing - it's a general truth.
If you view at a smaller size, then noise will be averaged out - but you don't need to throw away pixels and detail to do that.
The only exception is that some CCDs have pixel binning, which can reduce one source at noise at the cost of dramatic reduction in resolution. A few CCD based cameras I have do this for very high ISO and the results are slightly better than the alternative, but still awful.
AFAIK, there are no CMOS sensors in consumer cameras that do any kind of pixel binning. While it's easy to see how pixel binning can be implemented on a CCD, it's an entirely different thing with a CMOS sensor and it's not clear how or why this would be done.
You might gain some speed if bandwidth to your SD card is a bottleneck.
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