No claim is made about the accuracy of the depictions of Muhammad. The artists who painted these images lived hundreds of years after Muhammad and could not have seen him themselves. This fact is made absolutely clear in the image captions. The images are duly presented as notable 14th to 17th century Muslim artwork depicting Muhammad, not as contemporary portraits. See depictions of Muhammad for a more detailed discussion of Muslim artwork depicting Muhammad.
Similar artistic interpretations are used in articles for Homer, Charlemagne, Paul of Tarsus, and many other historical figures. When no accurate images (i.e. painted after life, or photographs) exist, it is a longstanding practice on Wikipedia to incorporate images that are historically significant artwork and/or typical examples of popular depictions. Using images that readers understand to be artistic representations, as long as those images illustrate the topic effectively, is considered to be more instructive than using no image at all. Random recent depictions may be removed as undue in terms of notability, while historical artwork (in this case, of the Late Medieval or Ottoman period) adds significantly to the presentation of how Muhammad was being topicalized throughout history.
These depictions are not intended as factual representations of Muhammad's face; rather, they are merely artists' conceptions. Such portrayals generally convey a certain aspect of a particular incident, most commonly the event itself, or maybe the act, akin to the Western genre of history painting. The depictions are, thus, not meant to be accurate in the sense of a modern photograph, and are presented here for what they are: yet another form in which Muhammad was depicted.
None of these pictures hold a central position in the article, as evident by their placement, nor are they an attempt to insult the subject. Several factions of Christianity oppose the use of hagiographic
imagery (even to the point of fighting over it), but the images are still on Wikipedia, exactly for what they are—i.e. artistic renditions of said people.