ORM's are hard to maintain on long lived projects. The database schema changes and the ORM code needs to be re-generated. A SP change means only one bit of your code changes also ORM support or even life doesn't last forever. We used LLBGen on a large C# project. We didn't have the working tools to generate the object wrappers after they went out of business. I had to rip out all of the LLBGen code and replace it with SP's. That code base went in place in 2003 and was finally retired this year.