I don't know about you, but I never use the King's Pawn Opening because of how weak it is in terms of structure and others. And openings that people hate or otherwise think are bad, such as the Sodium, Grob's, the Polish, Ware's, Kádas', Amar's, Anderssen's, Clemenz's, Bird's, and the Saragossa, are ones that I use and study, because of what they can be. The hammer will not reach its full potential when it is used as a shovel. Moving dirt is not the final goal. So, flank openings are not bad, because controlling the centre is not the final goal. In fact, I would actually say that no openings in files A, B, C, F, G, and H are bad at all (besides Barnes' Opening, which does nothing besides target the centre, and is, in my opinion, the worst opening on the board.).
A wall coming at you from the centre can be dodged easily. Castling, or just generally running.
Meanwhile, walls from both flanks give no escape.
In my opinion, studying is how to win games against common styles of play, while actually playing is how to beat people who use uncommon styles of play, like me. And being common and using the KPO makes my wins easier.
Using the King's Pawn Opening is like choosing grey as your favourite colour. Plain, old, and boring. Using a strange opening is like seeing the whole spectrum.
So, that's basically why I play chess. To prove people wrong.
(And, well, to have fun, of course.)
P.S. If you think Grob's Opening is bad, step on it when someone knows how to properly use it. (Henri Grob called [1. g4] the "Spike Opening". And, when you step on a spike, it hurts.