I think the reasoning is that the majority of studios also function as 2nd bedrooms in a 2 bedroom set-up. There is a VCR and/or DVD in the living room of the 2 bedroom unit. I agree that it would be a nice addition for them to put them in the studios as well.
If my memory is still functioning, the studios and Inn rooms at HHI and Vero do have a VCR/DVD. I seem to recall the explanation being that on rainy days the options for "entertainment" at these reorts is, of course, much more limited than at WDW.
