Well no one is saying it's not useful, but practical application and results are something else entirely. There's only so much you can do, there's only so much that can be rendered or loaded into a scene, the SSD isn't a replacement for memory bandwidth, it's absurdly slow in comparison. People also forget how fast Microsoft's drive is as well and what they're doing with it, at minimum it's a 40x uplift in I/O.
Look at what an SSD has done for Sony's marketing, a fucking SSD.... With a factually weaker system people just gloss over that in its entirety and shout SSD! SSD!
It's turned a marketing blunder into something questionably positive and the funniest part in all of it is no one can actually explain how it will factually benefit in game design over Microsoft's system. People seem to forget that just because something can hypothetically stream in data faster that it also has to render it, and Sony is at a disadvantage here, they're also at a memory bandwidth disadvantage which is far more important.