They should have had the PASMO/SUICA system available since it was introduced, like most bus/rail lines in the region. But they didn't budge at first since it cut into their profit margin. OLC was making loads of money from selling the the Disney PassNet pre-paid cards. Now, they are no longer sold.
FYI, taking the Disney Resort Line for just one or two stations makes it one of the most expensive rail lines to ride in the country on a cost per distance rate.