Does WordPress core have a voice and tone problem with its automated messages? That's the argument from Fred Meyer on WP Shout.
He gives a compelling argument:
One of WordPress’s greatest and most fixable weaknesses is its own use of words.
Words have power: power to define new users’ impression of the seriousness of WordPress and its creators; power to alleviate users’ frustration or aggravate it; power to provide information or smugly withhold it. WordPress’s current written content sporadically disregards that power, making WordPress seem like a cheaper, more irritating, and less well-executed project than it really is.
As a recommended fix, Fred advocates for the creation of an official core writing style guide, similar to Voice and Tone. He makes a number of interesting points and uses a variety of examples from core.
Zé Fontainhas also brings up a good point in the comments, citing that American colloquialisms can be lost on an international audience.