It is recommended that when used on Wikimedia projects images are given alternative texts − see http://enwp.org/WP:ALT
A user pointed out to me that MMV does not see make use of that, going as far as saying that it should be displayed too. I am not sure about this but let's discuss that.
For an example of image with an ALT text:
https://fr.wikipedia. org/wiki/Boite_de_conserve#mediaviewer/Fichier:Moneis_CNV00008.jpg
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=64519