Basically an aspx page will have controls like buttons and textboxes associated with them. Also the page will have a class file associated with it to handle the events related to the page.
If you want to create an aspx page dynamically, you cannot maintain the page alignment, controls and events related to the page. And also you cannot create an instance of a web page and dispaly it just like button control.
Although somewhat you can manage to create an aspx page dymaically using StreamWriter classes but it is not adviceable.