OK, I see what you're saying. Let me play devils' advocate. Let's say they switch ADR to 60 days, to match FP+. Imagine the mad rush to make reservations "that close" to someone's trip. Can you imagine the stress people will vent in not being sure they can get what they want so close to their vacation? Plus, let's say it's 60 days out from your big trip, you can make reservations starting at 7am. You don't get online until 7:30am for whatever reason. Everything is gone. Then what? I'd guess the uproar would be far worse than what it is now. Wouldn't you be furious that you're only 60 days away from your trip and now can't eat where you want?
For me, many of the frustrations that people voice about having to plan so far in advance and getting mad at WDW for it make no sense. I can understand wanting consistency from WDW, but I don't see it solving the problem. It's a very busy place. Guests are the ones snapping up the FP+, the ADRs, etc... It's not the guests "fault" because that's how the system works. Yet, at the same time, I don't see how WDW can avoid that. I don't know, but I would guess they strongly encourage far advance planning so that they minimize complaints of guests screaming at them "I tried to book my reservation two weeks in advance and I got nothing!! It's your fault because you didn't warn me!!"
To me, it seems like a no win situation for them. I really do understand why it's frustrating for guests, but I don't see where WDW is the root cause of the issue, or even worse what a good solution is.