WS is a unique course that has given us 2 very good PGAs and a Senior US Open. One can criticise the original design and wisdom of the faux links, and overkill of the 1200 bunkers, but now it is built and in the books as a major venue. I dislike the phrase, but; it is what it is.
That is why there are local rules to adapt to 'it is what it is'. The local rule is explicit and was fairly posted. You are on a unique course with unique situations of bunkers everywhere, and so you read the rule and go on. Everyone got through this except DJ and his caddie.
the PGA staff, marshalls, and crowd control were stupid to let the crowd encroach that far down into the likely area of possible play at that particular point, that they could trample and dirty up that bunker. If any other local rule might be added, it should be that loose impediments of an obvious man made nature, and not natural fiber, plants, or stones, (but cups, bottle caps, and the like) can be removed from these bunkers because they are too close or within where crowds go.
There are bunkers on this darn course next to the hot dog stands for "Pete's sake".
So, it is what it is, and adapt, and play on. Local rules are the defining aspect to all of this. Adapt to the local condition, post them, read them, and play on.