Oh, there are a bunch of low-level animators that 
would be very upset that their painstaking work 
creating douga was thought to be done by machine!!
I would also point out that genga are not series 
of rough drawings that get better and better...
The genga are the animation! Different animators 
draw more or less detail. They key cels are 
usually drawn by the top animator working on a 
sequence, the in-betweening is done by a lower 
level animator, and the douga is done by a 
"clean-up artist" which is considered the lowest 
level of animator because they don't create any 
animation at all, they just trace and refine the 
other guys' stuff. Actually, the key douga is 
probably done by a higher level guy than the 
non-key... at least based on my observation!
Oh, and when you have a drawing that has a line 
around it, especially if you have the perspective 
lines (the ones that go from a center point 
outward), that is usually a layout drawing. ;)
I personally love genga because they are what the 
animator drew in the process of animation. I like 
SOME douga (usually the key douga) but some of 
them look like very awkward tracing! 
Any rate, hope this helps.
Ryo