What you are saying is akin to somebody from the revolutionary war going forward in time to the age of the cell phone and saying "People are talking through these boxes but I communicate just fine with the people in my house. I don't need these boxes. It's okay if you do."

I'm not by any means suggesting that you're stupid or out of your league, but simply that you are talking about something that you are clearly completely unfamiliar with. Have you ever managed a team of people and projects? Once you do you will understand what an incredible pain in the ass it is to rely on email and spreadsheets. Full disclosure- I am NOT a 37Signals customer, nor do I know anybody affiliated with the company. Simply that project management software is a very real need for a very large number of teams. One of their partners created Ruby on Rails to create Basecamp, then released the framework for anybody to use and remained as a core contributor.