In Japanese, these aren't noun suffixes but number suffixes, known as counters or classifiers. You don't say, "*ninjin ga san" [three carrots], but rather, "ninjin ga sanbon" [three-cylinder-shaped carrots].
Mass nouns behave in a similar way in English: you don't say "*three breads", but rather, "three loaves of bread". Also, "head of cattle", "slices of toast", "sheets of paper", "items of cutlery", etc.
In Navajo, the classifiers are verb stems.
I just read this in the Wikipedia article on the Mattaponi River and it really tickled me. If only all language were so rational!