Considering they updated April just 10 or so days before the 1st I think you've got a wait for May or June.
As for why, no one knows. Not sure complaining would do any good. Would you complain to any other business that they don't provide you their operating hours?
I mean, they know what they are doing. They know people make plans but really, the segment that are uber planners, like those here at Dis, are small (VERY SMALL) segment of park guests. So it's impacting very few, as far as they are concerned. And those uber planners are going to adjust and go anyway. The rest of the guests aren't going to complain because Disney gives them more hours in the park