In web 2.0 circles, DIY (do-it-yourself) is shorthand for a publishing system made easier for the non-professional publisher. The irony police may just have to deal with the fact that DIY programs actually give the publisher less to do themselves, but hey...
DIY has thusfar referred mostly to web design, but now, with recent news that Microsoft's Xbox division is opening XNA Studios, the era of DIY game design is officially official.
But you, you're preparing to be a professional game designer, so how would building a game with a DIY system help you build a portfolio?
Game design is more about creativity and gameplay than it is about any specific tool or programming language. Many of our past game industry guests have told us that too many emerging game designers focus too heavily on how they built a game, when really, all anyone wants to know is, is this game fun to play? Is it good? DIY systems, like XNA, give you a chance to try out a number of game ideas, without investing countless hours into their creation. Can these designs, which do not show off your technical brilliance end up in a portfolio? Absolutely. And beyond that, the best "gamer-designed" games stand a chance to be picked up by Xbox, developed and sold.
Building a body of work means you can't ignore too many avenues for producing a working artifact. So don't. And when you do, come give us a visit. We've got a lot of people we want to introduce you to.