FFXII is the first one where you are unable to rename anything. (Characters, Summons, Airships...)
In FFX-2, you can at least rename the pets in the Trainer dressphere.
Unable to rename just adds to personality. It sounds weird in FFX when "Blake" (Tidus) is talking to Yuna (who you can't rename).
So in FFXII, I probably wouldn't have renamed anyone anyway. I'd be reminded of "Blake" (Tidus).