Because it sells? Or because sometimes a low seller will keep the rights so it can be sold again later in higher numbers?
The former, I think.
For as long as I've participated at Comicon, the last decade or so, I've also kept an eye on the sales charts for comics and trades/graphic novels. And throughout that time, WATCHMEN has been a regular presence in the Top 50 trades/graphic novels. It's not No. 1, mind you, but it's a modestly, consistently strong seller. This is true even when there are no movies or sequel projects coming out.
That's why comics shops and bookstores (who could give a damn about DC's corporate agenda) keep stocking it.
The lame projects that Marvel and DC publish just to hang onto a trademark, you don't see those on display five, 10, 15 years later at stores.
I don't think it's a nefarious scheme to deny Alan Moore his rights. WATCHMEN is a legitimately good seller. Under the contract that Moore signed, DC can keep publishing it.
I do understand Moore's frustration. In 1986, with the direct market still relatively new, who could imagine a comic book would be collected and kept in print for a quarter-century?
Jack Kirby was 44 when he did Fantastic Four #1, and had drawn his first professional superhero comic 21 years earlier. Was he wrong to be pissed off?
Depends on what pissed him off.
The Kirby/Moore analogy isn't a great parallel - and neither would be a Siegel and Shuster/Moore analogy - because the only thing they all have in common is they created something and then they sold it to a publisher.
I don't think Kirby wanted to own the Hulk or prevent others from drawing him. Kirby's main gripe, as I understand it, was that everyone got rich off his comics other than him, and that included his partner, Stan Lee.
I sympathize. As with Siegel and Shuster over at DC, at some point, the moral thing for a company to do - as the millions of dollars poured in - is share some of that with the guys who created the money-making properties, whether or not you are legally required to. That's a moral issue, not a legal issue.
Someone can correct me if I'm wrong, but I don't believe Moore claims to be inadequately paid for his work. In fact, he seems uninterested in money. What he wants is legally recognized control of what he wrote for DC, which I can respect, but ... that's not the contract he signed.
Given the track record of the comic book industry in general - and DC Comics Inc. in particular - and given Moore's fierce intelligence, I'm puzzled as to why he accepted some company manager's verbal assurance that he would get this one thing most dear to him, creative ownership of his stories. This would have been a relatively unique deal for DC in 1986. Why not get that in writing?