Sure the model may not be the best for keeping a cyclical market, but for the customers that already exist, advertising is how to attract them. His signature is a good start though.
But that is a good point for the non existing recurrent payments, less money over time - for both scripters & devs. I wonder why they changed the system, considering scripts usually require some form of upkeep, no matter how small. There was probably more people canceling payments before the next month, or being turned off from buying, assuming there was no way to stop monthly payments.
It would seem fair to maybe lower the initial cost, and make monthly payments mandatory, but if the above is a reason for stopping it, then I guess it makes sense to do lifetime with a higher initial cost vs lower monthly cost.
edit; imo that's not the only way to make money off scripts. You could make a script better than an existing one, and those who need it may feel obliged to buy it. I've done this many times.