Anything less would cause nausea.
VR’s best bet at mass market penetration right now is Sony’s upcoming PlayStation VR headset- it’s reasonably high end, paired to a cheap console that is also leading the generation currently, and it is only $399- which is far less than the other high end VR solutions. And Sony, of course, don’t want to poison the VR well by delivering subpar VR experiences on the PSVR, which will, for many, be their only exposure to the format, at least to begin with.
VR, as a format, requires high fidelity in its rendered images, as well as a consistently high framerate- any compromises on that front, and people using the headset can start to feel nauseous. This is why Sony is introducing workarounds like interpolation to ensure that PSVR software runs at a consistently high framerate.
Another measure from Sony towards that end- stipulating to developers that a PSVR game can never go under 60FPS. At their VR panel that Sony held for developers, they made it very clear that going to framerates less than that is a big no-no.
It’s good to see that Sony are trying to counter many of the problems associated with VR – such as nausea and health issues – beforehand, especially since similar problems gave stereoscopic 3D such a bad name just a few years ago. Hopefully the developers can find ways to make their games work at high framerates.