The biggest oversight in ASP.NET is the lack of an easy way to create fully functional nested grid and user control views (nested means one or more controls exist in one or more GridView cells; these controls may be grids or user control grids nested n-levels deep.) Propagating data downstream, permitting full editing functionality, and event handling are still very labor intensive. This is a glaring deficiency in the way you can develop Web applications with ASP.NET.
