As long as the service doesn't start sucking (like other monopolies and government services), I think there are a lot of benefits to being able to stream through an established player: it's not just about licensing all the content people want to watch. Supporting a lot of devices (I care about Linux support, A LOT), having agreements to cache content locally with ISPs to ensure performance, etc. I wouldn't mind having a different 4-5 apps for different shows, or switching services every few months. But if everyone went solo and they were all still figuring out how to support everyone's device and how to scale? Not gonna bother.

Hulu has started offering this as well -- HBO, in particular, doesn't really care about the streaming platform per se so much as making the content available. I think this is likely to be a path that others will take to take advantage of the fact that consumers may have a preference, and HBO would prefer to offer a nice standalone app, but perfectly happy to let customers choose Amazon/Hulu etc., for customers who prefer a different or integrated experience.

HBO is owned by Time Warner who is also a partial owner of Hulu. Makes sense for them to not care which platform you stream from since either is preferable to Netflix.