Headphones are a much better bang for the buck. My 580's with the equinox cable sound as good as the 20k revel salons. Needless to say, I can't afford the 20k for the speakers plus another 40k for all the electronics that one would need to take advantage of the speakers and to bring them to their full potential. The headphones can deliver equivalent fidelity for about 10% of the price and that's including a really good source and an amp.
What you don't get with headphones is the visceral feel of the music. The headphone images are much smaller and different than those of a speaker system. A good speaker system will deliver an image of the musical performance taking place right in front of you. Whereas with headphones, even the recessed ones, the image is smaller and more reminiscent of a small studio performance where you stand with the musicians and look out from the stage, rather than being in the audience and looking at the stage. Furthermore, it's much harder to share your music with others using a headphone setup or make love to music without getting entangled in headphone cords.
The speaker images tend to pull you in, whereas with headphones, YOU pull in the music (if that makes any sense).
However, the advantages of headphones are:
Full range drivers - no crossovers, no driver integration concerns
Acoustic space in your head - No concerns about room acoustics, damping, listening position of the speakers, standing waves, etc.
Price - There's no comparison here. I think it's because headphones are so much easier to make that it's much cheaper to get the really high fidelity system for a very, very reasonable cost.
Cabinet resonances - Headphones generally don't suffer from enclosure resonances and can thus produce a much cleaner sound for much less
Amplification choices - It's easy to make a good amplifer for a headphone than a speaker. You can have solid state, SET, Ultra Linear, OTL and other topologies without worrying about power requirements. Very little power is required to drive headphones, so your choice of amplifier topologies are dictated by your preferences, rather than practical considerations.
When all is said and done, I think that both headphones and speakers have their place. If I had the cash, I would have both. When forced to work on a budget, the headphone setup will get you much further than a speaker setup. That's why I think that most people, especially here are more obsessed over headphones than speakers. Simply because it's so much more affordable to obsess over a headphone setup and to experiment with different headphones, sources and amps.