I completely agree with you. There's always good and bad to presenting something like this. On the good side it gets people dreaming - it leaves enough to the imagination for it to seem amazing, for the possibilities to be endless. But unfortunately those things cannot map perfectly to reality, at least not all of them. Having worked on VS, I definitely know I can't build an IDE over night, not by myself, not even with 100's of people. And for some that will take the magic out of it initially. The way to combat that, though, is through transparency I think. I will be very open as the project goes on. I want people to know what we're thinking, what we're working on, and why we're doing it. My hope is that we can sustain a dialog as time goes on about how we as a community of creators go about creating things.
Despite the realities though, I will do my absolute best to deliver some of that magic. :)