Perhaps you should speak to the kindle people who are always asking for our feedback:P
Strangely enough kindle for PC shows the covers while the kindle does not.
Ask them why the publisher puts covers in the file if not for display purposes. Probably it is not intentional but is linked in some way to their idiot location number system. Like to meet the poor soul who dreamed that one up if he is not locked away for his own good
Myself, the only place I care about covers is in calibre. Makes it easy to see right off what book you are on and for me all of the different default covers get old real fast.
Used to be you could remove them and that is what I did if available covers were ugly.