When I was younger, I used to watch "Ripley's Believe it or Not" with my sister. Most of the stories I found fascinating, but there were few segments I just couldn't bear to watch. Included in my banned list were suspensions.
When I see someone doing it on screen, I can't help but imagine how it would feel to myself. I was baffled why anyone would want to do that to themselves. Why would they willingly put themselves through that much pain with nothing obvious to gain. Unlike gauges or piercings, it wasn't done to achieve a certain appearance. For things like tattoos and piercings, the pain is considered worth the desired change in appearance. It was done for the experience, and I couldn't imagine someone would want to pierce their body with hooks and hang by them just for the experience.
As I read Fakir Musafar and had a better understanding of the practice, I would say my view has changed only slightly. In modern times, most suspensions are fairly safe practices. The proper precautions are usually taken to avoid infection or permanent damage. And part of the reason why it is now safe is because the weight of the body is dispersed throughout multiple hooks. There is ideally no single hook that bears the majority of the strain. But just because you may not get infected and your weight is disbursed doesn't mean there is still some inherent level of pain associated. Giant hooks are being forced through the skin and then made to withstand a portion of a person's weight. Even heavy earrings are said to cause women discomfort and pain. Think of wearing a five pound earring. Yes, skin and flesh can withstand that kind of strain but it's not meant to.
There is an evolutionary reason for the development of nerves and pain. Most people and living creatures have a survival instinct. When something threatens their safety, there is an unpleasant feeling, and the individual is meant to move away from the cause of the discomfort. So when someone actively seeks a pain causing experience, it is usually considered some form of pathology. For instance, getting a dry tattoo is frowned upon because the individual is seeking only pain, and gaining no other obvious benefit. Most people that suspend claim that they do it for some other feeling achieved by suspending, not specifically the pain. But consider when people cut, they usually seek control but the pain accompanies it, and that is nonetheless considered a pathology. With few exceptions, like Professor Peace's friend who needs to suspend from his knees to relieve pain, suspensions are an act that seeks pain, and thus are considered by many to be a form of pathology.