Two things:
Try as I might, I can't actually recall anyone ever claiming that more strings do make better music.
And what exactly is 'better'? Is there a sliding scale of betterness? Who gets to decide if James Jamerson is officially better than Jimmy Haslip? Is it a competition?
I play five, for two reasons. One, because I play with a lot of brass and an ability to go below E often comes in handy in our songs. And two, because it makes my life easier in general in that I can go across the neck rather than up and down it.
You'll notice there's no "Three, because it means I'm better than a four string player".