[oh8eleven]

• Why Runners Don’t Get Knee Arthritis
  "One of the most entrenched beliefs about running, at least among nonrunners, is that it causes arthritis and ruins knees.
  But a nifty new study finds that this idea is a myth and distance running is unlikely to contribute to the development of arthritis..."
• Running Bad for Your Knees? Maybe Not
  "Not only is there no connection between running and arthritis, the new studies say, but running —
  and perhaps regular vigorous exercise generally — may even help protect people from joint problems later on."
• Runners are not giving themselves arthritis
  "The notion that the wear and tear of running causes arthritic knees and ankles is not backed up by studies."
• Does Long-Distance Running Cause Osteoarthritis?
  "... the preponderance of data seems to indicate that moderate levels of running do not increase the risk of osteoarthritis of the knees and hips ...
  The risks of running as noted should be weighed against the tremendous benefits of this activity to the other body systems ...
  This kind of physical activity has also been shown to help with weight control, to improve bone density, and to decrease mortality."

Running also has tremendous, positive benefits for those who suffer with mental disorders, ahem, cough, cough.

[SampleMan]

You might want to read those articles you posted. Especially, the last one:

"Physical activity is important in maintaining health. Long-distance and marathon running are relatively safe sports.1 Anecdotally, however, it is felt that “Today's runners are tomorrow's cyclists”—not because of a “natural progression” from one sport to the other, but as a result of joint injury.
Is there a causal relationship between running and osteoarthritis? The current data are based on small studies, and their results are often unclear. People engaged in sports or other physically demanding activities are known to be at an increased risk of osteoarthritis in the joints they use most (eg, knees and hips in soccer players, hands in boxers, lower backs in construction workers). Part of this apparent correlation can be explained by increased risk of joint injury.2 It would also seem logical that these groups would be predisposed to osteoarthritis from overuse injuries and not necessarily from trauma.
Osteoarthritis is generally divided into primary osteoarthritis, related to age and genetics, and secondary osteoarthritis, which is associated with a history of any kind of joint injury (eg, trauma, infection, surgery, mineral deposition, autoimmune disorders). Joint trauma can be acute or chronic, and pain intensity can be severe or mild. The trauma may be ligamentous, meniscal, or muscular in origin. Because of nonpathogenic but highly repetitive loading, overuse injuries may be considered a mild, chronic joint trauma. Such use is thought, with time, to deplete the joint of the lubricating glycoproteins, disrupt the collagen network, slowly wear away the cartilage, and cause numerous microfractures in the underlying bones.3"