I think another element the cost of maintaining it, supporting it, marketing, etc. hasn't been commoditized like producing brand new software. Those things take time to do properly and there are lots of people churning out a SaaS and then they get abandoned because its not fun anymore to do all the administrative/sales stuff.

I seriously don't think non-technical people are pumping out apps, probably never will. They simply don't have an interest and would rather just pay for a service. A HVAC, plumbing, or electrician company isn't going to write their own CRM system. Now they will price hunt those services so as software production becomes cheaper, I would expect SaaS margins to also be going down.