Fascinating talk by Malcom Gladwell from this years Pop!Tech on the difficulty people have in explaining their preferences, and in forming opinions of new things. Gladwell points his message in a slightly diffferent direction, but to me the communications angle is the key thing.
New stuff is always mainly about imagination. Even when you have it in front of you, before you begin to get an informal feel for what it does through using it, you rely on your imagination, and this might just be something I think - but i do think that our imagination is tied up in language. And it is not a natural ability to be able to express "new stuff", it takes skill and training.
Even with my limited experience in designing new stuff for direct use, the inability people have in verbalizing what they do, and consequently in imagining how it could be different, is the most basic thing you have to adjust to.