Kind of had a delayed realization—your bit above also demonstrates the time depth and origins of English terms. “Goose” has an umlauted plural “geese” because it is a native word, descended from Common Germanic; “moose” is a borrowing from a Native American language (which one escapes me at the moment, sorry), so the umlaut—which is now much more highly marked in English, where the default plural is by far -s—was not applied to it.
Kind of had a delayed realization—your bit above also demonstrates the time depth and origins of English terms. “Goose” has an umlauted plural “geese” because it is a native word, descended from Common Germanic; “moose” is a borrowing from a Native American language (which one escapes me at the moment, sorry), so the umlaut—which is now much more highly marked in English, where the default plural is by far -s—was not applied to it.