Nonparametric procedures are usually not our first choice among statistical procedures because

This is because they are less powerful than parametric procedures.

Explanation:

Non-parametric procedures are not as powerful as parametric procedures. Non-parametric procedures do not depend on assumptions about the shape or form of the probability distribution from which the data is extracted. A parametric test has more statistical power than non-parametric test. Some conditions of validity are required for the result of a parametric test to be reliable