Well, I love my mass produced Ridley, "happy" stem and all.

Head tube angle changes more than just the top tube length, and by itself it doesn't change top tube length much at all. If I had a head tube long enough to put the bars where I want them without a sloping stem, I'd need more slope in the top tube just to be able to stand over the thing (regardless of top tube length), and that would be ugly too.