Power to weight ratio, balance, engine design, and other things all come into play. "Bad for the motorcycle" implies an assumption even as the question is asked.
Generally, I think wheelies stress the frame and other parts (especially the chain, etc) of many street motorcycles in ways they were not designed to be ridden.
On a more personal note, I "flipped" a dirt bike in high school and narrowly avoided serious injuries. Years later in a small town where I lived a young man had sold his sport bike and the day before the buyer was to take delivery, he took it out for "one last ride." And indeed it was a last ride; he wheelied and crashed the bike and totaled it. Naturally, it was in his cul-de-sac neighborhood and he was not wearing a helmet. So while he did not die from the injuries, he spent months in the hospital and will forever require adult care due to the severity of his head injuries.
But as was noted by another poster, one can do as he pleases. Just count the costs beforehand and go for it...
Current ride: 2001 GL1800; Gone away: 5 BMW's, 4 Honda's, 3 Suzuki's
"The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -Marcus Aurelius
Last edited by basketcase; 07-24-2017 at 10:36 PM.