It's always been extra $$ to have options on your hopper ticket. The new ticket is customizing, it gives you more options of numbers of days and additions to those days. The people who weren't buying the hopper with options tickets, still have that option. But now with a shorter number of days tickets you can add the options when before you couldn't..........I think those are the folks they will pick up. To some people that money would be worth it to be able to pop into the water park a few days instead of the hotel pool. Our local waterpark is almost $30 to enter for the day and it's nothing compared to a Disney waterpark. If you take the $45 and divide by even the minimum of 2 visits that is only $22.50 each which is a savings.
And don't forget there are alot of people in the area who have water park only season passes, I know if I lived there I would and people will continue to buy the day tickets.