And why is a name that *might* bear some relationship to the shape any
more
"direct" than one that gives some idea of what the thing does?

Because over 3/4 of the population are "sensing" in terms of Jung's
typology - they use the information that comes directly from their
senses rather than theorising. What an object does is a further level
up in terms of child development, for instance, than what an object
simply looks like. In other words function is on a conceptual level
while image is mostly on the level of basic perception.

andy