As a business major and complete dork, I disagree. However I do know that the idea of writing a 15 paged plan isn't appealing to most people. Unless you are applying for a loan, you don't NEED a business plan, but you should make a mini one.
Just filled mine out and feeling ready to grow my business! A marketing plan doesn& have to be long and boring. Use this printable to set your marketing goals for the year. Bonus quarterly planners for mini goals and milestones.