1) Design research is an argument. In the research traditions I build on, research can be understood as an argument. There are several research traditions, and this is not valid for a lot of researchers within f.ex. medicin (positivistic research traditions deals more with objectivity and truth-searching).
Example: I study social media from a communication perspective and argue that typography, graphics, buttons and "likes" shapes the type of conversation in social media. This does NOT mean that functions and aesthetics DOESN'T shape the conversations, or that it is irrelevant to study the use perspective of social media. It just means that my argument is that a communication perspective is useful when designing social interfaces. As a professor said: "The thesis is not the history of what you've done, but an argument".
2) Research is about critique. Getting critique is valuable stuff, because it forces arguments to be sharpened. It is not so fun in the beginning though, when you've worked your ass off for six months with a hand-in of your proposal, and the only feedback you get is critique and a new date for a revised proposal… I think this aspect of research creates a downside too; academics are generally really bad at giving positive, motivational feedback on what you do. I have never seen worse in any other job!
3) Creating theory is designing. Working with theory does not mean that we're not creating, shaping and designing futures. In fact, that is very much what we do. Research by design is not about knowing theory and history, it is about using theory to get to something new, to move forward, shaping futures.