I wonder if the decision to animate the whole story means they've finally given up on trying to find the episodes of Power themselves, or they've managed to confirm the episodes are truly gone for good.
Given the timing, maybe they just wanted to do something to commemorate the 50th anniversary of Patrick Troughton's debut. I mean, that's nearly as important an anniversary as the one we had three years ago, because the introduction of "renewal" (later named regeneration) was the key to the show's longevity.