1) It's a technology, not a feature. Many companies, mostly Android handset makers but also Blackberry and Nokia, have included it in their devices as "yet another selling point". It was included not as a way to make a better device or experience for customers, but as a gimmick for upselling handsets.
2) It's insecure. Holy hell, Batman. Just spend a couple minutes reading through the security section of the NFC Wikipedia entry. It's insanely easy to read transactions remotely, modify data, and jam signals. Even more, there is no hint of security built into the technology. None. No RF signal modification detection, no encryption.
3) Unreliable. While it sounds like a good idea on paper, for the most part it just doesn't work very well in practice. There's too many subpar implementations in too many devices. Just because you have a good one in your handset doesn't help when most of the limited ones available in public are cheap.
There's a damn good reason Apple hasn't included NFC. It's broken. They definitely put out crappy products from time to time (don't forget Ping, iPod socks, Maps, Siri, MobileMe, and about 300 variations of the Mac before Jobs came back). But NFC hasn't proven to be something useful or valuable. They won't include it. Perhaps something like it in the future, but never NFC in its current form.