Because I am almost 34 years old. I've been dressing in tailored clothes for 10 years and I'm well set in my ways.
it's a point of pride for academics to dress like slobs. it wasn't always the case either. whom do we have to blame for this, anyways?
In my field, coat and tie is almost unheard-of. It seems to have gotten worse in the time since I finished grad school, since back then many of the old-timers would at least wear a coat, but they are now retired, and what's left is a lot of people in stained t-shirts and jeans.