Most of the market doesn't even know what the nexus line is.
Right - and many wouldn't care. They buy a phone because the price matches their budget, or because they like some physical aspect of it, or because of some feature their friends tell them is cool.
"Pure" android where they have to research and buy apps to match the functionality of their friends Touchwiz/Sense/iOS devices? Not so cool.
And regarding finding new features, you do that when you buy the phone and then maybe a year later when you get the next update. Along that line of thinking, how often does a nexus get an update to let you explore? A whole lot more often than any other line of phones.
Again, doesn't matter to most people. And given that google is moving towards rolling out new features via google play services instead of the base OS, it's going to become less important.
Don't get me wrong, I think there will always be a place for Nexus devices. They're a great way for developers to have a representative target platform to develop for. But most people don't "need" a Nexus device - especially with the advent of GPe devices.