Sure it's correct. At least in as much as it was causing far fewer problems than enforcing the window causes. That's why they went years without making any attempt to enforce the window. They made a mistake in thinking enforcing a 1-hour window was the right thing to do, so they corrected the mistake. Their original intent is irrelevant because they clearly made some bad assumptions. It happens.
Nothing has changed in that regard. What has changed is the new product they want to sell, and THAT is the only reason for the enforcement change. And of course none of us know how it will all work out since we have very little info on how the new system will work.
The only thing we should keep in mind is that this is clearly a fluid situation. As Xpass goes live and ramps up Disney is likely going to make changes as they go. After all, they had to do it with FP, and Xpass certainly appers to be a more complicated system. So I wouldn't assume that anything is set in stone, even including the new FP enforcement. If once they get XPass up and running they find the enforcement still causes more problems than it solves, they will backtrack again. I wouldn't count on it, but you never know, and that's the point as far as the future goes.
Under the current system, not enforcing the window was causing fewer problems than enforcing it. So Disney stopped enforcing the end time. Once they make that choice, their original intent becomes irrelevant. They made a mistake in thinking enforcing a one hour window was the best way to go, so they corrected that mistake.
So any problems it may have been causing have nothing to do with the change. The reason is the new xpass system, period.
You forgetting one tiny detail, majority used FPs on time and it did not cause any problems. It is not like change affects everyone, nothing changed for majority and because there were no problems before, it is safe to say Disney made no mistake. Many people just do not want to even try, well their problem, not Disney.