Does anybody know how come English retained some irregular plurals (feet, mice, oxen, children,

[Speck Tater]

7. "went" is a regular past tense.

But it's the past tense of "wend".

send -> sent
bend -> bent
wend -> went

Somewhere between 1200 and 1500 "goed" was replaced by "went", first by deliberate use of "wend" in place of "go", and later when the connection between "wend" and "went" was pretty much forgotten and "went" was just thought of as the past tense of "go". (At which time a new past tense for "wend" was invented: "wended".)

The process is called "suppletion", and is how four entirely different verbs with similar meanings gave rise to four different forms of what is now thought of as the same verb in "is, am, are, was".

It's also the way two originally unrelated nouns, "person/persons" and "people/peoples" got muddled together so that the singular of "people" started being used in place of the plural of "person". Why does it happen? Mostly through ignorance, the single greatest force in the evolution of languages. Back in the 1200's not only was there no Internet, there were no grammar police to tell the ignorant fools they were using English improperly. Their stupid mistakes have been cast in stone and are now our rules of proper English. Their errors have become our irregular verbs.

The phenomenon occurs in all languages. Look for it wherever one form of a word is clearly not from the same root as another. Mother->motherly is NOT suppletive. Cow->bovine is.