Singing voice is overrated if you can't make good music. Just like dribbling skills or whatever in basketball is overrated if you can't generate points.
But yes, Beyonce has a phenomenal voice.
But I couldn't even really care about that, the fact that she's one of the few broads saving R&B by being creative (or using others peoples creativity) for her past two-three past albums is why I think she's great. For years R&B was just about that same old boring ass love song recipe. No concepts to album, recycling songs worse than Birdman or Mike Jones and shyt, lyrically basic as fukk, but never got criticized for it. Then came The-Dream and revolutionized the game

.
That having a voice shyt nearly killed the genre, the weakest genre out for a while with no progression at all. That's why cats like Tank and Tyrese thought they were the shyt, when their music was simple ass songs that they remade 500 times, just cause they have a "voice".