It's disingenuous to say that this is the way the engineer intended it to sound. It's probably how it did sound to the engineer, but that's not the same as how he or she intends it to sound. Any competent engineer knows that people will be listening to the music on a wide variety of sound systems.

The NS10 has been out of production for years, and I haven't seen them in a studio in quite some time. Though, when I was in college (I went to college for audio engineering), every studio I worked in had a pair (in addition to one or two other types of monitor).

It is true that for a decade or two, the NS10 was the monitor on which more records were produced than any other. And, they are reasonably accurate. There are more accurate speakers than the NS10, even at similar prices, but part of the value of the NS10 was that you'd have them wherever you were working. The mastering engineer would have a pair of them, too, so you'd know everybody in the path from tracking to cutting the master would be hearing roughly the same thing. But, it's worth mentioning that I've never been in a professional studio that only had a pair of NS10s. They were considered the sanity check speakers...not the speakers used for all of your mixing and such.

Anyway, the newer models (HS series or MSP series) from Yamaha might be a good choice, if you want good reference monitors.

But, a reasonable level accuracy should be the goal of every transducer. Just because consumers make often make poorly informed decisions based on marketing and tricks played on the ear (because a "hyped" sound, like the Beats headphones and devices, will sound louder and thus "better"...but will also be more fatiguing and will have other negative effects on your listening experience) doesn't mean people who know better should just shut up and let manufacturers do so without criticism.

NS10s are so popular because they're so non-complimentary. Yamaha (and I've read conflicting accounts) either deliberately created a speaker that was so non-flattering to any audio, or accidentally released a product that became a studio mix engineer hit for the same reasons.

I've heard producers and studio engineers say that if something sounds good on NS10s, it'll sound good on anything.

This is the same reason professional mastering engineers will sometimes insist on listening to mixes on average car stereos, ipod headphones, and cheap consumer audio systems. It doesn't matter how good it sounds on your $100,000 studio system if it sounds terrible to 99% of the population.