Because people released good paid scripts 6-10 months ago, most of the people purchased these scripts 6-10 months ago.
After this time the revenue was so small that we, scripters, were barely making any money, because everyone who wanted to purchase a script, purchased a script already in the past.
Since scripters are making less and less money, developers also are making less and less money.
We needed a change of system, since the old one with one-time payment scripts doesn't work for both customers and scripters.