Why would shoes be made to squeak? So that you couldn't sneak up on people? I really can't imagine any other reason.
My father grew up in London in the 1930s and 1940s, and I remember that he used to have a funny little saying about squeaking shoes that went something like, "If a man's shoes squeak, it means that he doesn't own them". Hence, whilst his statement was joking, I think that it indicates that squeaking shoes weren't thought of as a good thing.
Essentially, squeaking can be caused by one part of the shoe rubbing against another part of the shoe, such as the tongue rubbing against the inside of the shoe upper or the shank of the shoe rubbing against another part of the sole, or it can be caused by your foot/sock rubbing against the inside of the shoe.
If the latter, using talcum powder, wearing thicker socks, or installing some pads inside the shoes could help. If the former, particularly if the squeaking seems to be coming from inside the sole, it would well be difficult to fix and could be a manufacturing fault.
Thanks for the information, Journeyman.
Obviously, the squeaking of my shoes does not come from accessible parts of shoe rubbing against each other (as I could cause the sqeaking from just bending the shoes with my hands a little). Should I write Meermin about the issue?