I think the point I am trying to make here is that it's a *big* task to fix word boundaries for every case (every word-related key binding multiplied by each language/major mode I use!).
I presume that Emacs hackers either a) put up with it or b) spend a lot of time fixing each case until they are happy.
I suspect the answer is b. ;-)
I wish there was a single minor-mode that fixes all the word boundary issues for every major-mode I use! I can but dream. Or maybe I will get round to doing it myself one day! ;)