I'd say that it was too soon because the potential new audience for superhero titles other than the squeaky-clean DC titles was my generation, and our parents weren't buying us any. The older kids, who might have read Captain Marvel and Plastic Man and even the tail end of the DC Golden Age books when they were little, were buying horror and crime comics until those went away. It wasn't until the more numerous generation that began with the baby crops of the late '40s started making our own purchasing decisions that new superhero titles became viable. Maybe there's NOT a causal relationship there--I certainly can't prove one. But I think it's there.
Who am us, anyway?
--The Firesign Theater