As a new member, I'm somewhat hesitant to wade into this discussion, but here it goes...

I am a history buff, generally snazzy dresser, and recovering clotheshorse. Because of that combination of interests, I am very familiar with both conventional and historical sartorial "rules" (aside: "etiquette" or "conventions" are probably more apt terms).

From that experience, I would say the "animosity" (aside: "annoyance" or "frustration" are probably more apt terms) with the kilt-hire industry is twofold. First, out of practical and economic necessity it leans to the generic. For example, it usually provides customers with ghillie brogues and white hose for all occasions, because stocking buckle brogues as well, and a plethora of colored and pattern hose is too impractical. And, this has led to a homogenization of both highland and Saxon formal wear, which is sad if you care about such things. Second, customers usually rely on kilt- and tuxedo-hire firms to tell them what is and isn't correct. But, too many of these firms blithely tell customers that whatever they happen to have available is correct for the customers' needs in the interest of making a sale. Which, or course, it pretty crappy. And, this has led to "dumbing-down" of both highland and Saxon formal wear, which is also sad if you care about such things.

Finally, the best advice I ever read regarding sartorial rules/etiquette/conventions: one should learn them before choosing to ignore them so that ones style is transcendent, not transgressive.