Probably, most of us agree, "too many rules = too many hassles", but it solves nothing as it stands since the rule is already there.
Here's a very real scenario: A keen VMXer travels thousands of Km to the Nats, spending $1000 on fuel alone, & taking a week of his holidays or time w'out pay to get there. He's racing for fun, goes hard at it, has a ball & manages to get on the podium. The guy he pipped for 3rd place doesn't like getting pipped, notices that his F11 has a downpipe when it was originally fitted w an up-pipe, & protests that his pipe does not "follow original lines". (Putting up the $50 to protest is a pittance compared to what the other guy has spent just to get there.)
The only thing the officials of the day have to go on is the rule as written. Obviously the bike was not originally fitted w any kind of down-pipe, so the protest is upheld. Understandably, the guy is shattered, even tho he's only there for the fun, & he probably never comes back. Many are rightly disgusted & the flow-on disillusions others as well.
We can say all we like about it being bad sportsmanship, unfair, ridiculous, mean-hearted, pedantic, etc, but such people are out there. As the saying goes, "there's one in every crowd", & it only takes one. With younger racers & their diff attitudes comes younger officials (eg their Dads) also w diff attitudes.
It's a very real scenario for those who live a long way from the action. There's already a precedent. Something almost identical happened to John Boag at the WA Nats over bolts instead of rivets. My perception of that action is that it had a massive impact on pre75 racing, esp at Nats level. People rightly think, "If thats how they're going to play, I'm out of here". We can ill-afford another like action.
But nothing will change if all we do is discuss it here. Somebody has to fill in one of those rule change forms & get it reworded (or dropped completely). Until then, the bloke in the above scenario is very vulnerable. As Doc says, better to do it now before it happens & avoid the considerable pain, repercussions & disillusionment.
PS, GMC yr pipes are very tastefully done, blending modern pipe designs w era-sympathetic lines extremely well in a way most of us would regard as entirely appropriate. What we need to avoid is things like the lowboy pipe on the YZa in VMX mag several issues ago.