Suggestion: Writing a business plan from three perspectives

Did you ever write a business plan? Can you remember the starting point of your plan? I assume you started with a great idea you suddenly had. After some research you probably found out that the idea needed some reshaping. Some elements are simply not possible to operate, others are too expensive. When you speak to potential customers you suddenly realize that the business needs to be changed to meet customer needs.

So, basically I think you can write a business plan from three perspectives:

1. Idea centered (passion is main driver)

2. Restrictions / resource centered (financial situation is main driver)

3. Customer needs centered (marketing is main driver)

Do you agree with this 'theory'? Are there more perspectives to write from?