Is it just me, or do road bikes with unusually tall head tubes just plain look odd? Seems that the larger the bike size, the weirder it looks. It's not quite as bad in the smaller sized frames.
What exactly is the design objective? Seems to me that a less steeply angle top tube, with or without the head tube extended above the top tube, would look much better.
(2012 Jamis Quest shown below)