Most comics creators are not millionaires, and if DC is screwing a highly visible, highly successful author, I have to wonder how well they're treating the less visible creators

Ya all those millionaires comic book artists - you're totally out of touch with what marvel and DC are paying.

Comics creators are famously exploited. Superman's creators died in poverty, and most work by Marvel and DC is performed as "work for hire", i.e. not generating royalties for actual authors. This is also why authors increasingly try to publish independently, but that also means working on brand new series that may or may not attract any popularity and actually generate profits. For one Mark Millar or Todd McFarlane there are hundreds faring worse than Joe Shuster.

todd mcfarlane and mark millar got rich going into business for themselves, rather than working for DC and Marvel.