In all seriousness, that question has more answers than a wizard can shake a wand at but I'll address a few of them:
1. I like double meanings.
2. I wanted to create a fantasy story that was funny and light but with a bit of practicality...
but mostly laughs. The concept of a Wizard's Guide to Wizardry seemed to fit
that bill.
3. I wanted to make fun of many common fantasy (and wizardly) conventions.
4. I wanted to try something entirely different but loosely connected to to larger world of Ea'ae explored in the Chronicles of the Fists series.
5. A few other, as yet undisclosed, reasons (feel free to make up your own!).
*Reader submitted question.