Hm. Why don't they just limit the # of characters that can be typed in the title text box?
But maybe because when you paste a value longer than the max it just chops off the end. That sounds good until you consider that the ultimate goal is to have people re-structure their titles to fit the constraints as best they can rather than just providing a "preview" of the content (e.g. first line of the content).
For example I may paste in:
> LambdaLite: A functional, relational Lisp database written in 250 lines of Common Lisp
That's 87 characters. It would get mangled to this:
> LambdaLite: A functional, relational Lisp database written in 250 lines of Comm
So now the person entering the title has to paste it into notepad, fix it, and then paste it into HK within the length requirements. That doesn't help anyone.
Instead just accept an infinite length, and provide feedback on it allowing people to alter the title to perfection until the error goes away, no mangling or deleting title contents.
Server side validation is entirely appropriate.
I think limiting the number of characters is a good solution when Javascript isn't available, but warning the user that their input is too long is a more friendly solution where possible.