An overpowered Pyro allows for a larger entry level, without resorting to handholding which is good.
Too bad the PVP suffers from it, apparently (though i don't do pvp, and as far as i know, pyro is not very used in PVP anyway).
The long wind-up for non-Dex builds combined with the short range makes it a non-starter in high-level, one-on-one PvP duels, but it's still popular with invaders.
There's one Pyromancy buff that's commonly used even in high-level dueling, but that's actually because it's glitched in such a way that it's way more powerful than it should be.