The definition of "appropriation" includes theft and forgery and pretty much any kind of copy catting you can think of so that term is bunk. Even RonZombie would be covered by that term if he started selling his own Wacky sketches. Other artists illustrate Superman comics so it makes sense collectors would want their sketches. Nobody is continuing or re-inventing the OS characters or gags in new works unless you consider the sketches themselves to be the new "works". I don't think anybody would want an Andy Warhol autograph from any artist other than Warhol. But I'm fine with a Jay Lynch Blunderbread because Jay is far too significant a part of the OS to be dismissed for such a technicality. I don't see collectors saying they want a sketch because it's funny or attractive. All they talk about is having one of each artist, one of each character, a set from each series, etc.
No, I strongly disagree. There is no theft, no forgery or even copy catting in any of these WP sketches. Topps owns the rights to the characters and the original images. Topps has hired these artists to use these characters and to draw them so no theft. They are hand drawn on new cards with a logo and back clearly stating what they are so no forgery. They are drawn in the unique style of the artists and many times with artistic license and changes to the source image so no copy catting. I have seen Fred's sketches and a large majority of them ARE "continuing or re-inventing" the OS characters in new works. Brent had the OS characters being eaten by a crocodile.
Ronzombie would not be covered by anything as he does not have permission to use copyrighted images for shirts to sell for profit and he is not making a unique artistic statement by taking a Topps owned character, lets say, the Quaker Oats duck and just redrawing it for his shirt to sell. Warhol and other artist have been able to get away with using popular culture images in the same way a political cartoonist can use Obama or GW Bush's images because they are making unique artistic statements. You need look no further than Wackys themselves. If Topps takes the Trix box and reproduce it they are in violation of all kinds of laws. Topps makes Tricks and it's a parody and legal.
We are getting off track of course though. The single simplest thing is Topps can and does hire different artists to do new interpretations of their wholly owned characters in the exact same way DC hires people to work on Superman. I think you need to leave nostalgia out of it and you can't start making exceptions for someone (Jay in this case) which totally torpedoes your reasoning for not wanting to see these types of sketches.
I don't quite see your Warhol autograph thing making any sense since we were taking about drawings not autographs. Of course no one would want a faux Warhol autograph from another artist but I'd bet if Roy Lichtenstein did a drawing or painting of a Warhol work people would want it. Putting what you wrote in Wacky terms you just said that no one would want a Jay Lynch fake Norm Saunders autograph which is true. But everyone would want a Jay Lynch drawing of a Saunders painting. And it already appears that people want a Fred Wheaton drawing of a Norm Saunders painting.