It sounds like ASP.Net is trying to make you think like you're working with a Windows application and thus it's doing some magic for you down in the HTTP to shift state betweeen browser and server.
ASP.NET's basic 'advantage' is that it pastes a VB like event driven model onto a HTML form. The only advantage I can see of this is that it might make it a little easier for a Windows programmer to move to ASP.NET.
The huge downside of this that Lincoln has discovered is that it is hard to mix your own controls and javascript with ASP.NET's built in ones. The event model and flow of the code get screwy.
Jay