1. I don't like writing superhero stories and would rather not work in the genre.
2. The writing and editorial staff are a clique at this stage. Breaking in to the Big Two would require too many compromises, etc. I would be better off establishing a name outside them and waiting for them to approach me.
3. I'm not American so that's another problem; it's not the 80s/90s anymore; there aren't miniature booms going on that require a large intake of fresh talent constantly. The market is contracting and will continue to contract.
4. As above, a combination of the 2, and 3. Unlike the Japanese market, production of comics in the US is saturated; the market has enough writers/artists and unless I work for below market value or have gained popularity and such, I won't be brought on.
5. I don't like Marvel and DC as companies, let alone most of their output. They have had great comics in the past and I'm sure they'll continue to make a few good pieces, but to be quite frank, there's no future there at this rate and I'd be better off working on my writing and scripting and getting work elsewhere.