When holding an art/craft event, how important is it that all vendors 'match', so to speak? If it isn't important at all, why do so many organisers seem dead-set on doing it anyway?

I've been to several smaller shows where all the goods from t-shirts to tote bags have the same aesthetic and it's clear that the look is what's preferred by the show organisers, but I have to wonder if people who make decisions based on what they like are really considering their market. What appeals to the late-teens hipster might not make the thirty-ish professional want to reach for her wallet, and what appeals to her might be something different than what interests the retired fellow shopping for gifts for the grandkids.

Unless one is specifically promoting a look or a genre, does it really do anyone any favours to have everything in a show look like variations of each other? Is it really that hard to allow a little variety? When I go to these matchy shows, I rarely stay long because by the time I've seen ten booths I've started to feel like it's deja vu all over again. I don't doubt that many others there to shop get the same feeling and, like me, head elsewhere.