I would say they definitely are important.
Among the typical reasons (shared vocabulary, not reinventing the wheel) they are a stepping stone to learning good software design. The majority of the design patterns out there start off by programmers with a good sense of OO principles applying what they know to solve a problem, and noticing that other people are coming up with the same solution. If you think of design patterns as a cookbook to solve the current problem you're stuck on, they're not really useful, and this is where you see the "design pattern hammer" come out and complicate designs.
If instead think of it as a window into good object oriented design you start to see how valuable they are, i.e. thinking in terms of the principles behind the design patterns instead of the specific design patterns themselves.
