Well, I think your suggestion is good, but if you ask me, I did say that it's too early to impose such limitations in the chat box, since most of the users here are pretty new and still learning about the forum, there will be constant questions and suggestions, and sometimes, using the chat box is the fastest way to find solution to a very pressing issues.
And aside from the above, not every many people use the chat box after all, the forum is still growing and not crowded enough just yet to keep the chatbox extremely busy at all times, maybe when we get to the stage where there are several users using the chatbox, then that would be the best time for a limitation like to suggested to be implemented, implementing such limitations now will just be as long as turning off the chatbox feature, many users will ultimately stop using it.