But the "is there a line or isn't there" is almost half the fun IMO.
It prolongs the fantasy if you're not pg but want to be, for me it softened the blow a little bit rather than getting just a bald "Not Pregnant".
My actual BFP developed very slowly so at first it looked as if there was no line, so I was all "huh, that's that then.." and slowly and surely a line developed and I was "Noooo... it CAN'T be...!" A lovely moment (sigh)