A drawback of NMR crystallography is that the method is typically more time-consuming and more expensive (due to spectrometer costs and isotope labelling) than X-ray crystallography, it often elucidates only part of the structure, and isotope labelling and experiments may have to be tailored to obtain key structural information. Also a given molecular structure may not always be suitable for a pure NMR-based NMR crystallographic approach, but it can still play an important role in a multimodality (NMR+diffraction) study.
Unlike in the case of diffraction methods, it appears that NMR crystallography needs to work on a case-by-case basis.  The reason is that different molecular systems will exhibit different spin physics and different observables which can be probed.  The method may therefore not find widespread use as different systems will require tailored experimental designs to study them.