Spherical coordinates systems are always a tradeoff between usability and simplicity. Plus Codes are certainly simple, easier to calculate, and consistent, but

Spherical coordinates systems are always a tradeoff between usability and simplicity. Plus Codes are certainly simple, easier to calculate, and consistent, but UTM has clear advantages in that it utilizes a Mercator projection adjusted for the contour of the earth, so that distances remain close to scale within any given grid zone… …except in Norway. In Plus Codes, the scaling is lost, and the distance covered by coordinates of equal precision changes dramatically with latitude. Of course, there is also the fact that the mapping ellipsoid used by UTM changed at some point, so old coordinates can be off by up to 200 meters compared to the current mapping. But the current system has been in use long since the advent of GPS, so it's really not an issue.