Hmmm a tough one...design-only though i think.
As for why... I guess I drifted into the graphic design area of things after I got disillusioned with the (as I saw it) pompous-bullshit-spouting world of fine art. Always been more of a realist than a theorist so creating things for a purpose appealed to me more. Trained initially in fine art and illustration then moved towards graphic design, typography, design history, design theory etc then into the interactive elements of design.
The shift towards web based design happened due to market forces I guess - more work, more money, more opportunities.The building side of things has never appealed to me - and if i dont want to do something then I dont do it. Simple as that really.
I enjoy what I do, have a nice stressed free work environment and I'm perfectly happy with that for the time being.Oh and I'm a stubborn sod.