Is bisexuality enough? Not really, I think. As a label, it's not highly useful. If somebody says to me they are gay/straight/lesbian, I understand that they are interested in and at least theoretically capable of sex, romance and long-term relationships with people who posses the gender identification of their choice.
Not so with "bisexuals". I know of all those fancy terms like "bicurious", "hetero/homoflexible", "bisexual lesbian", "pansexual" etc., but the sheer popularity of "bisexual" will ensure it's survival as an umbrella term that covers all the above variations and then some.
Are there genuine Kinsey 3's out there? Must be. But how many and how to tell them apart from the rest, if everyone's bisexual at least in principle, theoretically, never say never, "I fall for the person not the gender" -way?
Don't get me wrong. It's wonderful that more and more people don't auto-assume they're straight just because everyone else seems to be. But an intellectual nod to the bi potential in all of us is a far cry from actually being available for courting by both (all) genders.
What I really want to know is this; if a girl calls herself bisexual, does it mean she likes to kiss girls when she's drunk, enjoys threesomes with her boyfriend (because let's face it - he wouldn't do it with another guy for her), had a girly crush during her teenage years, has agreed on an OPP and really has no choice but to seek out other girls...?
When does bisexual mean "yes, I am open and willing to engage in long-term committed romantic relationships with members of both (and in the case of pansexual, any) genders"? Because frankly, I don't have time for the others. Casual has a lot of good to it, but I just don't want to sex up anyone who is a priori uninterested/unavailable for a relationship with me that goes beyond the hydraulics.