Basses can be BGVs, too.
Contemporary music seems to have a fascination with tenors. I’ve got no problems with tenors. Where I do have a problem with is when a singer’s talent is determined more by the upper extremes of the vocal range rather than their ability. Not all voices are made equal. Just because a man struggles to reach the G above Middle C in full voice does not mean he’s worthless. What it means is that he shouldn’t be singing that G.
Three-part harmony is standard… but don’t forget that the most important note – aside from the melody – is usually the unsung one in the bass. Who says it has to remain unsung? And who says he can’t double one of the other parts in a lower octave?