Shooting is using deadly force. Shooting a suspect to intentionally avoid fatal wounds is a TV myth (most episodes of Quinn Martin's "The FBI" ended in this way, for example).

Every LEO in the country is taught to shoot only when deadly force is necessary and to shoot for the center of mass (and continue shooting until the suspect is down).

Shooting with intent only to inflict an immobilizing but not-life-threatening wound is inherently wrong and has been held actionable by the courts. If the LEO had the luxury and time to even consider such a tactic, then aim and fire, then by definition no innocent life was in imminent danger, and therefore the use of deadly force was excessive.

And if you take another look at your source, you'll see that there is no stated intent to only wound the suspect in that German case.

A good study of such situations is the Massad Ayoob book In the Gravest Extreme.

Anybody that shot a handgun at the range will tell you that hitting a small moving target like a leg is not a guaranteed shot even by an experienced shooter (add stress, low visibility etc and this becomes even trickier).

If you come at cops with a knife I think it's "reasonable" they shoot you. What is not reasonable in the case of US cops is that they seem to shoot even non dangerous people and get away with it.

This is also very true, and it makes a difference.