Ah, in the case of developer originated SaaS, then sure, doing a SaaS offering rather than donationware might lead to more income for the developer, but I don't think that free software is alone in this - plenty of proprietary software that would once have had fixed boxed releases is now subscription or SaaS based too.
Recurring income is a stronger business model, nobody's denying that, but that doesn't mean it's an improvement for the user or that those producing software with a goal of financial gain would have just released standalone open source software if only free software licenses had been more sympathetic to their needs. Rather, I think if SaaS did not exist, if their first goal is revenue, many of these groups would have just released straight up proprietary software.