Indeed. This isn't "milking" it's being released on a new format, nothing else.
Now, it is milking if there's a better/more feature-laden edition released a few years down the road on Blu-Ray.
Well they'll have to revisit again when there is a 3D product to sell.
Even then 30 hours of extras is only 5 per movie, there's a wealth of people never interviewed for DVD, hours of valid doucumentaries that could be sourced.
I'm not sure there will ever be enough said about the films for some fans!