I can understand your point of view. I am a software developer myself, and things like this for the "ease" user experience are a high priority in all software. Why make things difficult for users.
Sure I can use the who panel etc, but the info is available at the time they join, its a small change to the text given to the other party members which will make things much easier and simpler for them.
As for the follow on warnings about xp loss, I included that as an additional feature request beyond the basic one as it would help inform new players about game mechanics they may not be aware of.