Whenever a new technology is developed, the first applications mimic existing stuff. The first cars looked liked carriages. It took a while to get to a car design that actually works in a functional sense. This is called the Horseless Carriage Syndrome. It can be observed everywhere; especially in web design.
The solution is in really getting to know the raw materials we're working with. It's time we get to the next step, and for this we - the designers - need you: the front-enders. So quit bitching about ignorant designers designing heavy and unusable websites, and start enlightening them. What opportunities are waiting for us to be used in finding the internet's true voice?