Like drinking alcohol, smoking pipes has a negative connotation for some people. Excessive use of anything can lead to an addiction that is unhealthy but when done in moderation, most things are perfectly acceptable.
Even losing weight can be unhealthy. Someone who is obese can benefit from sticking to a good diet. Losing weight to the extent that it becomes anorexia can be extremely dangerous. So even doing something that is good for you to an excess can have a negative effect. People like to watch television to relax and escape for awhile. When the television starts to take the place of spending quality time with the family, it can be a problem. Salt is something else that is fine as long as it is used in moderation.
Many marketing campaigns characterize various habits as being extreme behavior. Cigarette manufacturers make it look like people are constantly smoking. Various medical organizations take the opposite approach and warn of the dangers of smoking and encourage people to quit. The same stigma associated with cigarette smoking has been applied to smoking pipes. Enjoying the occasional cigarette is less likely to cause harm. When someone becomes addicted, usage increases and so do the health risks.
There are many people who simply cannot control their impulses. They possess addictive personalities and practicing moderation is a real challenge. Alcoholics who want to drink a lot feel the only way to control themselves is to not drink at all. Having even a single drink can lead to destructive behavior.
Certain people should not be smoking pipes or drinking. If there is a chance of addiction, the vice should be avoided altogether.