I've come to realize that I use a lot of gradients and drop shadows in my work. I've made a concious effort to use other design elements but some sites just end up with a bit o shade in them. You could almost call it my "style" but I don't agree. Looking at my porfolio one thing many people comment on is that I have the ability to come up with a different solution for each of my clients. There are some common threads but each design is unique to the character and personality of the client.
I attribute this to my broad range of skills. Being well versed in photography, color, illustration, and flash as well as photoshop means that the possibilities are wide open. A lot of people are experts at photoshop but not so much at illustrator. You can tell by looking at their work. Its the combination of those programs that makes anything possible. Moreover, it is the lack of any kind of technical limitation or lack of focus on technology that allows me to have a wide vision.
BUT, I will say this about gradients and drop shadows. They are a trend. Web2.0 is full of them. And they are important in web design for a good reason. The early days of the web were ruled by bandwidth. Flat, one color GIFs were easier to swallow than textured jpegs. As we move to high-bandwidth pipes detailed, photographic, textured imagery are now easy to incorporate. The flat, bitmapped graphics of yore have actually gained retro appeal.
Gradients and drop shadows are an effort to mimic reality. When you design a print piece the end product is effected by light and shadow. A lot of my designs have subtle light and shadow treatments. Sometimes you can barely percieve the color shift, but the end effect is an element that has depth and texture to it. Interactivity can go a long way, but the touch and feel of print won't be replaced for a while. Even the smell of paper and ink adds to the experience. You can smell a good quality paper with a spot varnish.
Of course, a gradient and a drop shadow can be an easy way out. A default look. The important thing is to create a design that fits the client or project. And, knowing how to use the drop-shadow filter in photoshop and creating the interplay of light and shadow on a screen are two entirely different things.