WVR isn't the only situation where one needs to look over the shoulder. Good visibility matters literally from preflight checkup onwards.In any case, if you need to look over your shoulder in a stealth plane, you have already screwed yourself bigtime
And WVR is still relevant enough to matter - especially when stealth becomes widespread.
We've already gone through near- or totally blind cockpits in the 1960s.I can see practically see armored windowless cockpit in next generation of combat aircraft...
No point going there again unless wide-angle VR environements will evolve enough to outdo human eyes.