When it comes to sex, the difference between top and bottom is pretty clear: someone pokes while the other spreads. The cliche is that tops are masculine while the bottoms are more femme. Some ego dudes will proudly announce themselves as “Total Tops” like they’re some sort of superior sexpert.
Variety, yes, is the spice of life, whether over the course of a relationship or during a single sex session. “I don’t do that because I’m a top (or bottom),” just puts whole big chunks of possible pleasure off limits. It might be better all around to approach the top/bottom thing as a sliding scale, with “total top” and “absolute bottom” as the endpoints — most of us falling somewhere in the middle — and with the whole top/bottom dichotomy taken with a grain of salt. After all, those of us who know the pleasure of getting our faces humped hard wouldn’t say it’s an inferior thing to do, and those of us who have to get it up and keep it there while screwing know the grave responsibilities and hard work taken on by the poor, hardworking top. (Maybe that’s why it often seems that there are so many more bottoms than tops out there.)