title: Why should a web architecture be loosely coupled?
body: <p>When I look at ASP.NET MVC projects I everytime see loose coupled architecture.</p>
  
  <p>For what do I need a loose coupling in a web architecture (if I do not make unit tests)?</p>
  
  <p>What are <strong>advantages</strong> and <strong>disadvantages</strong> of this?</p>
  
  <p>What is the <strong>main reason</strong> to decouple layers/classes?</p>
  
  <p>What if I do not want to change my DAL for example? I mean when shall I change my whole DAL?! So I could couple my DAL to the UI. What is bad with this?</p>