How do you fix that?
Not by fighting the urge to type, but by feeding it.
You mention "coding one more feature". Where did that feature come from, you or your users? If you consider "intimate contact with your market" as a box on a flow chart that provides input into "features to code", any self-respecting geek would understand how important it is as a critical step in the dev process.
"Intimate contact with your market" is just as important for development as it is for marketing. Don't allow yourself to play the introvert card when pieces of the puzzle are still missing.
Doesn't mean you aren't right and people shouldn't try though.
However, a great coder can probably get away with being a decent marketer. I just think that it's the extreme case of genius coder + clueless marketer that is a killer.
Better would be to morph marketing and development into one by maintaining intimate contact with your market as you develop your product. You end up building what they want and have a head start on your sales cycle when you're ready to release.