Yesterday someone emailed me saying that they downloaded "Like.fm for Firefox" and then proceeded to ask me what the site's address was (it's Like.fm).
However cases like this are still the exception. Bad user experience design usually leads to clueless users. So it's not a matter of intelligence or technical acuity, it's all about how experienced you are with the interfaces and how well it's designed to be familiar to you. Obviously if you are the designer you're going to be more familiar than a new user. But it won't matter if you're using wormholes for your internet backbone if it's well designed even Abraham Lincoln will be able to use it.
That being said not all user interfaces should be dumbed down as much as possible. It just has to be as familiar as possible to your target user base.
However cases like this are still the exception. Bad user experience design usually leads to clueless users. So it's not a matter of intelligence or technical acuity, it's all about how experienced you are with the interfaces and how well it's designed to be familiar to you. Obviously if you are the designer you're going to be more familiar than a new user. But it won't matter if you're using wormholes for your internet backbone if it's well designed even Abraham Lincoln will be able to use it.
That being said not all user interfaces should be dumbed down as much as possible. It just has to be as familiar as possible to your target user base.