mongodump currently outputs a lot of things to stdout, which can be easily redirected when used in scripts.
The message "connected to: 127.0.0.1" is sent to stderr, which doesn't really make sense, because it's not an error.
I don't believe anything other than errors should be sent to stderr, especially from a tool that's supposed to be used mostly in automated environments.
This would cause sysadmins to:
1. Send everything to /dev/null, which would cause them to not know if anything breaks
2. Write output handling scripts to inspect the stderr output, which is an inconvenience
As far as I understand now, those messages are common to all the tools, and something might break if this gets changed.
A possible workaround would be to provide a `--quiet` switch, which would not output such messages.