There are cases when certain projects (like ArbCom elections and Dispute resolution noticeboard replies) where there is an arbitrary 400 or 500 word count limit. It would be nice if there was an indicator on the inputbox itself someplace that returned a character and word count.
I do foresee the difficult part of this being the counting of words that are transcluded as template calls, but I don't think it needs to be that detailed or accurate. Anyone that tries to game the system by transcluding a bunch of words in a template will surely be called out on it. This may need some more input/thought/development before it can be implemented. See https://en.wikipedia.org/wiki/Wikipedia:Help_desk#Word_Count_Template.3F