a +1 button so that if you agree with a poster, you can click this button and it adds to the total?
There's obviously nothing in the way of implementing such a feature tech wise.
The ramifications of such a "like"-button are probably unwanted, though.
I don't believe that the majority of bitcointalk users would approve of a system where "fishing for compliments" became a major motivation for posting. In a system like this, majority opinion tends to become dominant, which is the opposite of the kind of academic discourse many of us like about bitcointalk.
TL;DR: +1-button? -1.