One hypothesis is that Disney increases park times based on predicted crowd levels. The higher the predicted crowds, the later they keep the parks open. People seem to think that the current data showing a decrease of park hours from June 2015 to June 2016 has proved this hypothesis to be wrong because they are assuming that Disney has cut hours while attendance is still increasing, but what if that is not true? What if Disney predicted June 2016 crowds were going to be lower than June 2015 crowds and adjusted hours down accordingly?
According to Josh on EasyWDW:
"Over the first four weeks in June, crowds have been shockingly weak. I’ve been working on a new song for the website’s debut album titled, “Where Have All The Tourists Gone” loosely based on this Paula Cole jam"
http://www.easywdw.com/easy/blog/to...nu-review-and-a-general-magic-kingdom-update/ (June 29, 2016)
and
"Summer crowds continue to be weak into July. Magic Kingdom, which has historically seen a capacity closure on Independence Day, didn’t get anywhere close this year."
http://www.easywdw.com/easy/blog/magic-kingdom-pinquest-review-as-wildlife-looms-heavy/ (July 7, 2016)
I don't know the answers either, but I think it's a plausible explanation that June 2016 hours are shorter than June 2015 hours because predicted attendance was lower than predicted attendance last year.