Medicaid and Medicare part D?

Okay, so I went to that website, medicare.gov, and apparently I couldn't really search for the answers I was looking for. So I'm going to ask people here who may know this. Before this whole medicare part D mess, my grandma was receiving prescription drugs fine with medicaid. Now that part D is here, does she absolutely need it to get her prescription drugs? Can't she just continue replying on medicaid to get them? Is part D really necessary? She was fine with medicaid before, but ever since like two years ago, she was automatically put on a part D drug plan, but I don't get it, is it required for her when she is automatically enrolled? Medicaid still pays for your prescriptions drugs, don't they? Why medicare part D?

When Medicare/Medicaid was set up, Medicaid was defined as a policy of last resort. Any other insurance plans will take priority over it. So, Medicare Part D takes precedence over Medicaid prescription policy. If Part D doesn't cover a particular drug, Medicaid will cover it. It'll be blind to you. The way a dual eligible is covered is complicated. Medicaid does pay money into Medicare Part D. Your grandmother is not paying for her Part D coverage. She cannot legally waive out of Part D, if she does, she'll forfeit her Medicaid drug coverage. If she doesn't like her insurance carrier, she can change it between November 15th and December 31 every year.
Seniors who were just on Medicare, until 2006, did not get any prescription drug coverage.
Overall, the clear majority of seniors like Medicare Part D.