Be formal, but not too formal

Every now and then I hear different opinions on weather or not to do business plans, SWOT analysis, schedules, road maps, etc. I'm surprised how extreme some positions are. There are people who believe that hundreds of pages of documentation is a must before any actual work can be started, others take it for a total waste of time.
Well, all these documents have a purpose - to provide information and help you keep track of your goals. If prepared properly they can be extremely helpful and will help you stay focused on what you should do. They are also great reference point in many cases. Your mission statement should make it much easier for you to create products that are consistent with company's values and goals. Having market segments nicely described will help you discover new opportunities and new ways to reach your target. Periodical SWOT analysis will make you more aware of the risks your business takes.
So why so many people are so negative about them? Well, it seems they just haven't seen these tools implemented correctly. They usually associate business plans with many long, bloated pages of worthless forecasts and predictions most of which have no solid foundations. And sadly, that's true in many cases. Here's good news - it doesn't have to be like that.
All these tools are great as long as they serve their purpose. Having these done just because it's "the right thing to do" will get you nowhere. First of all make sure that you and your team knows exactly what to expect from each of these tools. Secondly remember that the output has to be readable and informative above everything else. I'd rather have single page of analysis I can understand and draw conclusions from than 10 pages of overly detailed, incomprehensible reports, which will just waste hours of my precious time.
To be honest my company is lacking in the area of formal documentation. This is something I want to work on over the next couple of weeks. What's your experience with using these kinds of tools in small companies? Did it pay off? Did it turn out to be helpful or did it get lost and forgotten?