I can't imagine having a frame built custom. I'm not that far off of Mr. Average and my needs are not out of the ordinary. Now if I were a frame-builder myself I'd totally build myself a custom frame -but I'm not an the added expense just isn't worth it to me. I'm pretty happy with the way a standard C&V Raleigh Sports works for me.
If I needed something a little different I wouldn't be against having a frame modified, adding extra lugs, or stuff like that but I don't see myself starting from scratch.