I think the majority of wordpress website owners have a very basic understanding of technology. This means it's possible to build and monetise plugins that do t

I think the majority of wordpress website owners have a very basic understanding of technology. This means it's possible to build and monetise plugins that do things you and I might consider trivial - and that's a good thing if it's done well and customers derive real value in exchange for their $/£'s. It's extra overhead for developers to update an application to fix security/compatibility/bug fixes without including new features too. There would need to be two versions of the app, one with just bug/security fixes and one with bug/security fixes + new features. That's two code bases, two sets of testing required, two sets of releases and release notes/change logs. As a result, asking customers to pay for a year of upgrades/support seems fair. If customers continue to derive value over that year, they can purchase again for another year. If not, they can abandon it.