Just IMO, but I think that the mental 
readjustment many people are making to 
considering sketches as worthy stand-alones, due 
to the switch to CG animation, are making many 
people take a closer look at sketches from cel-
based shows.  (Never mind that we could use the 
switch to CG as an opportunity to find a cheaper 
hobby...)

Whle cels are preferable, too often, they're 
already owned, or way out of price reach.  If I 
couldn't afford a particular cel from a 
particular show, I'd be quite happy to get the 
corresponding genga, if it had nice detail and 
some color (as delicate as it usually is).  (Of 
course, I've yet to find sketches offered from 
the first Samurai X OVA, so it seems the gods are 
still amusing themselves.)  

Some really good sketches have their own beauty 
but still won't be appreciated by everybody - as 
with all things, personal taste rules. (And the 
ability of one's scanner to capture delicate 
nuances! One shot too much of brightening, and 
you're posting a virtually blank page!)