Suppose that I want to add a field. Someone else adds it to the table. I have to then add it to the view, insert procedure, update procedure, and possibly a null procedure. I further add it to the object-relational mapping layer, and then to the unit test. That's 5-6 files.
If the object-relational mapping layer could also do the job that the stored procedure does. That would cut out 2-3 edits. Furthermore those are the biggest edits.
If I was reworking the system, I think that you could still have stored procedures, and have them be autogenerated from code. However the system already exists, and at present it is easier not to have to rebuild it.
Cheers,
Ben