Why should a web architecture be loosely coupled?

Question

When I look at ASP.NET MVC projects I everytime see loose coupled architecture.

For what do I need a loose coupling in a web architecture (if I do not make unit test

Answer 1

A loosely coupled architecture will help you when your application needs to change or grow. And any non-trivial application will eventually need to change or grow.

If you design with a loosely coupled architecture, only a few parts of the application should be affected when requirements change. With a too tight coupled architecture, many parts will need to change, and it will be difficult to identify exactly which parts will be affected.

One of the main benefits of TDD, in my opinion, is that at helps promote a loosely coupled architecture.