Consider first that adventure racing is a horrible spectator sport; that is, there aren't any spectators. Further, participants rarely, if ever, know what they will be doing at a particular adventure race. Thus, unless there is significant media coverage of the race, no one is going to hear / know about these quirky challenges unless one of the participants informs them. When hearing the tale of an adventure race, if the most attractive portion of the recap is this quirky challenge, then the person considering adventure racing is likely better suited to make their audition tape for a reality show.
One of the elements of adventure racing that I love is that you never do the same thing twice. Even though ten races might have the same four typical disciplines, each race would be considerably different. However, I do appreciate the unusual. The idea of adventure racing suggests that most of us do appreciate the unusual to some degree. Including some reality show type challenges can work very well at an adventure race if the challenge is delivered properly. In planning an atypical challenge the race director needs to recognize that once the race starts, everything that the racers are required to do will effect their placing. Adventure races are long, some very long and in excess of several days. It's easy to forget that every second counts! Still, even a fraction of a second is all it takes to decide a winner. If an unusual challenge is going to be implemented into a race then it's paramount that the challenge doesn't contradict the nature of a race.
Natural Selection Adventure Racing host an 8 hour race, Who's Your Daddy, every year in Fredericton, New Brunswick, Canada. One of the most heralded parts of the race is a tire pull. Racers are required to drag a large tire for 1000 m, and in addition to the race winners, perhaps the equally coveted titles of 'Daddy' / 'Mommy' are awarded to the male / female with the fastest tire pull time.
The first two people in the video are myself and my teammate for the race Kelly Murray. Neither of us were that fast at the tire pull, but we did finish second overall!
What makes the tire pull acceptable is that the fastest and strongest racers are rewarded; it's a challenge that's very much within the image of a race. What makes the tire pull a success is that it has a huge macho factor. People train to be the 'Daddy' / 'Mommy' and they talk smack about who is going to succeed! People make a specific effort to attend the race in order to be the 'Daddy' / 'Mommy.' It's a challenge that generates enthusiasm and is a fine example of an atypical challenge that will do adventure racing well with respect to increasing our numbers.
An example of a poor challenge would be if racers were required to complete a Rubix's Cube. This type of challenge does not reward the fastest, strongest, fittest or the most adventurously skilled. Though there may be some reward for logic or general knowledge, it's not a direct correlation to who would presumably be the best adventure racer. A Rubix's Cube challenge might generate some laughs from the more light hearted participants, but the likelihood of it frustrating a veteran adventure racer is more probable. When you've discouraged a regular adventure racer, said racer is less likely to attend / hype the event or other events from the race director, thus the sport may suffer from the poor choice of a challenge.
Creativity does have it's place in adventure racing, but not at the cost of the race.