The importance of measurement in quantitative research is that

Measurement in quantitative research delineates fine differences, gives a consistent yardstick, and enables precise estimates, so all of the above holds.

Delineating fine differences between cases is one clear benefit of measurement.

Providing a consistent device or yardstick is a second benefit.

Allowing precise estimates of the degree of relationship between concepts is a third benefit.

Measurement translates abstract concepts into observable, comparable numbers.

Good measurement rests on both reliability and validity of the instrument.