While T2* value will be reflected in the signal line-width observed in the spectrum (field homogeneity dependent), the real T2 value is of high importance for many applications such as in MRI, petrophysics, proteins dynamic studies, among others, as it is a property of each spin and its surrounding.
References :
* Chapter 9 from J. Keeler, Understanding NMR Spectroscopy (2nd edition, John Wiley & Sons, Ltd, 2010.)
* S. Meiboom and D. Gill, Rev. Sci. Instrum., 1958, 29, 688-691.