Halfwit Hobbit

[Galin]

Appendix F notes that Banazir 'Half-wise' was originally a nickname, but being a word that had fallen out of colloquial use (along with Ranugad 'Stay-at-home') it remained as a traditional name in certain families.

So maybe the meaning wasn't so thought about among Hobbits, especially when shortened to Ban perhaps; but in any case some people today name their kids with no idea what the name means, or originally meant.