Getting feedback from your user community is really important, but, of course, your community isn't necessarily building your product. There are lines to be drawn, right? You can't have the inmates run the asylum...
...or can you?
That's a little bit how I feel now. I feel like I'm the customer. What would make my product fun for me and my friends? What would make me want to use it? What's in it for me?
I can't say enough about being a user when you're building, but not how you might think. Like just the other day, I started a Photobucket account. The things that I thought were important... like an uploader and tagging... not in there at all. But yet, its just as popular as Flickr. I didn't find the UI intuitive at all, but then again, I'm not every user.
Being a user means you see what's out there and play with it, and instead of passing judgement, you try and understand why something is popular. You match feature sets to usage and popularity. Its the difference between being a pet owner and a zooalogist. You don't have to love the stuff... just understand it and learn from it. Of course, you build up a passion for it, and that's important, but pet owners don't always know the most about their pets, because they don't study their pets. They interact with them and build emotional relationships with them. Zooalogists try not to start with that and try to keep it "professional" so that you can take a stop back now and then I've had to remind myself to do that and to keep an open mind as to what works and what doesn't, lest I overdose on my own Kool Aid.