I think I generally agree with the NGC grade here but also understand why others would grade AU.
Huge numbers of coins in Meiji issuances generally have the same problem which is that the reverse gets disproportionately affected with any wear. In this case the obverse is really beautiful and would easily merit a choice grade or even a gem, however the reverse would likely be an AU. For the meiji Japanese coins the grading agencies tend to take a blend just because this difference between reverse and obverse is so common.
So generally for all the Meiji coins I would always check the reverse first.
Nice find as these are in practice extremely difficult to find in MS - it took me a couple of years to get almost every 1 yen in MS (apart from the 74,75,and 79). It took me over a decade to get the 10 sens (except the 1902)