Why can't powerful features be done in an intuitive fashion? Smart UI design will allow for that. The more typical argument is one of simplicity versus functionality. But if you choose functionality, why not put in the effort to make the features as easy to use as possible?

The expert user was a casual or novice user once too...

If I find something unintuitive, then I will avoid using it. If I find something intuitive, then, provided its s\for a task I need to do, I willo use it and become an "expert user". I think software needs to be intuitive (or, more importantly, intuitive to the target user), yet still cater for the expert power user by providing shortcuts/macros/scripts/keyboard commands/advanced features etc.

I'm not a UI expert and definitely need to improve things with my site, but I've found that most non-tech users can't be bothered to do much of anything that requires a little thought. If you're not spoon feeding it to them, they don't want it. This is why drag and drop website creation is so successful.

I find this argument completely incorrect... Was Google made for expert users? Were ipods made for expert users? Providing an interface which allows users to accomplish a complex task and in the process users know what they are doing is the essence of the whole ui.

First, it's not necessarily a tradeoff.

Second, it should be intuitive to your target audience, be they experts or casual users.