JSP is just a fancy way of defining how your Servlet should look like.
Everything you write into JSP goes either directly into Servlets service method or new Servlet mehod is created when <%! is used.
With Serlvets you would need to put your HTML code into double qoutes and since JAVA doesn't support multi line strings this would be very annoying.
After changing Servlet Web Application needs to be reloaded while JSP is reloaded automaticly.