In my opinion this is the first step of them bringing the ability to pre purchase
genie+ for your vacation. If they get rid of the park pass reservations they can use some of the data from this to see what parks people might be going to on each day if they buy the non park hopper genie+.
Honestly that brings up another question, for the vast majority of Disneyworld visitors(not those of us on forums talking about planning our trips a year in advance) I wonder if the majority of people don't buy park hoppers, but there's no way for us to get that information.