As part of my multidisciplinary practice, I consider myself to be a free-spirited advocate of any medium. Good design is good design anywhere you create it. And it becomes good design by deciding how presentation and structure is best going to serve the user. Does a design choice make it easier to understand the message or facilitate an action? Let's flip that around. What if an action should be difficult?
Because I think these basic questions are answerable anywhere there is a product to be used, I've learned how to hand-code HTML emails from scratch and implement them in multi-channel campaigns, build web pages and program Ruby web apps. Also, making things is fun.