Writing to markets

I was telling my friend Ken Scholes this morning not to think about markets while writing. This is my general perspective — write what you want, or need, to write, and think about markets only post facto. The one significant exception I make to this is themed anthologies or invitations, where there is an editorial requirement in play.

It occurs to me I might not be right. For example, if I had a perfect understanding of a market’s requirements, could I or would I write a story aimed at that market? I’ve never been in F&SF. Should I study GvG’s editorial selections closely, and try to write into whatever “sweet spot” I might perceive? Frankly, that strikes me as rank madness. My auctorial voice is what it is. Whether or not it matches GvG’s editorial voice (or anyone else’s, not to pick on the fine Mr. Van Gelder) is entirely a matter for them.

What’s your perspective on writing to/for markets? Why does it seem to be ok to write to a themed market but not so ok to write an open-ended market?