It was intentional, and it was discussed. I forget where. I know Andrig Miller was involved and agreed that not doing i18n for the CLI was appropriate and wasn't a violation of the Andiamo objectives.

People will script the CLI, so having output vary based on arbitrary environmental issues that affect choice of locale is not what we want.

There's an argument for adding i18n to certain things, e.g. exception messages that no one is likely to look for in a script, but I suspect the decision making about what's appropriate for i18n and what isn't would quickly get murky and in the end would produce a mess.