At the end of the day security costs money. Should security consultants offer their services for free? Should security guards work for free? Should DDoS protection be free even though it uses expensive firewalls and bandwidth? Should security audits be free? Should badge scanners be free?
Adding a "login by google" button costs a few hours of developer time. I've done it myself, it isn't a whole lot of work.
On the other hand, I'm dealing right now with two services (NetSuite and Certify). Both "support" SAML, but they offer no direction on how to set it up or any sort of support for the setup. The documentation that is out there, is out of date and/or incorrect. Even though they offer these as paid additions, they don't really support them.
Anyway, that's where I'm coming from. I'm not trying to get into some deeper meaning debate here.
