This is an interesting concept.  I like the idea, but I do not think it needs to be mandatory.  I went straight to solo practice after law school.  It wasn't easy, but I didn't need a residency to do it.  There were many times that I had to do a lot of extra research to get things done for my clients.  I did the extra work - with out billing my clients - because it was general knowledge that benefited me more than the client. 

The trade-off for me was that I didn't make much money the first couple of years.  But, over time I have become much more compenet at my expense, not my clients. I was always very careful not to take on a client if I didn't believe that I was compenent to represent them. 

There is certainly a problem in the legal profession and many people who need representation cannot afford it.  An optional program like a residency might help young lawyers find entry level positions and lower the cost of legal services.  However, a young lawyer willing to put in extra hours, that are not billed to the client, can provide the same benefits.  He just has to be willing to work harder those first few years to do it.

Best,
Robert A. Franco