Constitutional Interpretations: Who Cares What Dead People Thought?

Just saw a video clip of Jon Stewart interviewing an American constitutional scholar and historian and part of the interview touched on the interpretation of the 14th amendment in the way the founding fathers intended for it to be interpreted.

I am no legal scholar myself, and I barely read anything that goes beyond 10 pages predominantly filled with drawn cartoons (2 if those pages consist of just words), so it is safe to say that I've not read any countries' constitution.

What I found strange though is our obsession with ensuring that the constitution or any other legal documents are interpreted as closely as possible to the intentions of a group of people who have been dead for decades or in some instances, hundreds of years ago.

Maybe an alternative strategy would be to disregard, to a certain extent, the intentions of the creators of such documents, people who lived in a different time under vastly different circumstances, and to focus on interpretations which are fair and equitable in our present day society.