Insecure? You're the only one that's ever insecure about the precious PSVR not being treated as some king of VR. 120Hz is needed for PSVR because they need reprojection from 60Hz which will make up a lot of the available content, especially for the base PS4 model. 90Hz gives an option for devs to target to give a better experience without the performance penalty of 120Hz. 120Hz rounds out the trio and has the best temporal experience, but at the cost of significantly reduced graphics quality.
As for the 90 for PC devs, that's a joke. Any game designed for 90 on the PC (which is just an arbitrary number - you just tune your assets, effects, etc to reach that number), won't straight port to the PS4 at 90. The base GPU and CPU for the PC space far exceed the PS4's power. Any port will require changes to work on the vastly different hardware. It'll be up to the dev whether they want to continue to target for 90, or go for 60->120. They could also hop to 120, but if they're capable of doing that, then they're on the simplistic side of things to begin with.
So no, the panel wasn't chosen because 120 is better than 90, and they wanted to beat the PC in some stupid spec war where no game is even forced to use it (and most wont). It was chosen because 60Hz reprojected is easier for the PS4 to handle, and for that they need a multiple of 60. Any slower panel and they'd be doing something like the Vive with 45->90 which sucks. Any faster would be a waste. You choose your panel for the average use case. In the PC's case, a 90Hz limit was a decent tradeoff on already expensive gear. PCs were already struggling to hit 90, so 120 wouldn't have made a ton of sense for gen one. Few games would hit 120, and 60->120 makes little sense in the PC realm.
