Spot on. Don't club me for saying this, but once I got my MBA, I was able to see tech products from more than just a nerd's eye view (I did my undegrad in CS)
The same for me (Mechanical Engineering undergrad). I think part of the problem stems from thinking that marketing == advertising. In fact if you are going to create any part of a business plan, I think it should be your marketing plan. It will force you to really think about your product, what features will bring the most value to your customers, and how to reach those customers.
Hehe.. anyone thats started a company here knows full well the importance of marketing... especially those who've failed =)