I think that a matching sketch gives one more of 
an incentive to buy the cel (kinda like with a 
background).  In quite a few cases, the douga is 
just as beautiful or even more so as the cel 
itself.  It's a shame AIC had to scramble their 
sketches (although I managed to find 2 Tenchi 
cels with thier matching dougas [one also had a 
matching genga]).

I'm happy that my Relena op cel came with a 
matching douga.