Fair enough - I guess you guys have spoken. Just to prove I’m not secretly a Protoss hater in disguise, I have suggested buffs before, albeit more subtle (although I’m happy to drop the Robotics Facility requirement on it):
Really, letting your Void Rays charge forward as part of a deathball is the sign of poor control, but I can see the drawback to Flux Vanes in that case. It’s more the issue that it makes a fleet of Void Rays lethal with tech-sniping. Compare 6 Void Rays to 12 Mutalisks (same supply cost, although much more expensive on minerals and gas)… they’re not as good at killing workers, but they can make mincemeat out of static defence and kill key structures incredibly quickly if you’re caught out of position, and then make a hasty retreat.
I suppose I also look at the other Fleet Beacon upgrade, Anion Pulse-Crystals… which is 150m 150g for a +2 attack range buff, which is primarily to help deal with Mutalisks in PvZ and might have a niche use in PvP when the opponent also has Phoenixes… i.e. it’s not as notable.
Originally, Flux Vanes was removed when Void Rays still had to charge up their attack in Wings of Liberty, because I believe it made them too strong in PvT (they wrecked Vikings and Medivacs).