Microsoft recommends that a web application should be having these layers.

Presentation - BLL - DAL - Database

I am trying to understand the significance of the BLL and went about reading the same from http://msdn2.microsoft.com/en-us/library/Aa581779.aspx

Most of the times the BLL only delegates the job to the DAL and does not do much. Isnt this an unnecessary overhead.

Is it a good idea if there were some kind of hybrid model where Calls are made through the BLL only when bussiness logic demands and lets the DAL be contacted for other call where there is no business logic involved ?