Head voice and breathiness do not denote the same thing. Nor does head voice imply a lack of projection (otherwise you'd not hear too many operatic sopranos beyond the front row). If you listen to Maria Callas, head voice is certainly not cutesy 'little me' singing.

Bonnie's insights sound about right - it's all about where your natural register break occurs (unless you're a trained singer who's spent years ironing out said break). And I'd imagine this applied equally to lots of traditional singers - perhaps those who we've heard on recordings are those whose deeper, earthier voices appealed to the collectors?