i dont know, I think its because its views conflict with the views of hapkido or something, and I forgot to add im not very competitive

My old martial arts teacher loved it when I joined the wrestling team, He wasnt blind to the benefit of crosstraining like alot of martial arts instuctors are. ( he just reminded me not to use joint locks becasue they are forbiddon)
I guess it cause most are in it for money and they see it as a potential loss of money. 
Mine taught our group of 7 for free in the school gym everyweek, he was clearly doing in only because he loved fighting arts of all kinds, no money earned. In fact he spent money on our eqipment (gloves, head gear, targets) and never asked for anything back. Damn he was a great guy, I wish I could still train with him, but he moved.

I second Steven's comment about Rings...they rock.

The thing that I've come to realize is that I'm happier when I go with the flow a bit and vary the things that I focus on over time. Some months that's Parkour more than anything, with lots of supplemental training, at other times it's much more Olympic Lifting with some supplemental gymnastics and very little Parkour if any. If I dwell on one goal or the other, I get stressed. If, on the other hand, I try everything any just follow what happens to catch my fancy at that moment, then I'm productive and motivated year-round.