This is a maturity thing. There are very few complex applications on the web. Very few. And, most are not used by the average users.

Plus, those few non-trivial sites people do use (Amazon, EBay, Google, Paypal, Yahoo, etc.) have had thousands of man-years devoted to their design, making it as easy and intuitive as possible.

As a web-developer who builds non-trivial apps, I feel your pain. We are simply not provided with the resources to do what we are asked to do. In that, we are not alone. Very few professionals have the luxury to have everything they need (let alone want!) to do what they're asked to do with excellence. *shrugs*