Much of the issue here is about level-setting expectations. Frequent flyers have an expectation that they will be able to redeem miles for tickets at levels which are announced by Delta.
Delta's credibility suffers tremendously when you can't find tickets at those published levels, the itinerary is convoluted and inconvenient, and/or you need to call a live person to make an award reservation (triggering a fee).
Doesn't much matter whether the expectations are not being met due to technology, policy, and/or some conspiracy theory of where Delta wants to take the SkyMiles program in the future.
Marketing 101 -- when you extend a promise to your customers, find a way to keep it.