The real reason is this: If you once had a cardiac stent put in but now are on meds, don't smoke, eat right and exercise everyday you might just not be able to get a medical while the guy who doesn't know it but is more likely to have a heart attack then you are, might pass. If you are taking meds for mild depression, you might be denied your medical but someone with undiagnosed crazy might pass his exam. If you have controlled diabetes you might fail your medical but someone who is about to have an aneurism might pass. It's a farce and sport pilot proves it. I certainly don't think it's more dangerous to fly a 172 than a 162. It's good for aviation because many highly experienced pilots who are a hell of a lot safer than those who passed their medical and have lots to offer the community have been unnecessarily forced out and that's wrong. What truly sucks is that I would like more options but even though I know I am healthy enough to fly, I will never risk the exam and possibly lose even my chance to fly sport.