Is the resume feature so difficult?

[mac1165]

One of the most convenient features of DVD is the ability to stop the movie you're watching, turn off the DVD player, and in most cases even remove the disc from the player itself, and the movie will resume from the place in which you stopped when you're ready to begin watching again.

I'm sure this has been asked before, but I've never seen a good explanation, but is it too much to ask in the supposedly awesome upgrade of Bluray to include the same feature? I understand that this is not the fault of the Blu-ray player itself, but of the source disc not having the code for it. I know that it is possible as I've seen a few Bluray discs that do it, but the vast majority do not. What's up with this? I can't imagine that including this feature is cost prohibitive or degrades the quality or some other reason that prevents manufacturers from including it.

Give me the resume feature over BD-Live any day.