maybe its because the code section does not know which layout you are loading in design/code time?
if i am not mistaken, after you do activity.loadlayout, only then the objects in the view are accessible. thus we declare the variables in the layout again in code to at least have access to its attributes during code.
The layouts are completely decoupled from the program code. This allows you to switch layouts at runtime, load layouts to panels and TabHosts and more.
I think the answer is 'no the designer does not automatically create code members for each and every view added to a layout'.
Would you really want each and every view in a layout to have auto generated member code?
Each view that had member code generated but was not accessed via code may even be a waste of resources - depending on the number of views in your layout..?