I do think that math and geometry are useful and when not considered to be magical is valuable to know.
I consider the issues involved in the recurrence of the Fibonacci ratio in nature to be fascinating and no doubt informative of something.
So it's probably not just math and geometry that is useful for making oneself appear to be a wizard - just about any advanced knowledge can be employed that way with less-educated people.
Meaning that there's certainly nothing intrinsically wrong with them but rather the use to which they can be out in the "wrong" hands