The only reason for asking for not making an interpretation in accordance with the historical intent is, off course, that it makes the constitution more or less meaningless. The purpose of the american constitution was off course to restrict what the elected officials may or may not decide upon to do. If you say that whatever majority presently occupying the seats of the house of representatives and the senate may interpret it however the wish its a useless document. That it doesn’t serve its historical purpose and allows the elected representatives make whatever laws they see fit.
However, the US constitution is not without fault, because it is a document created by mortal men. But, as stated earlier, it allows for making ammendments. The problem with this is that if to many ammendments are made and the ammendments come into conflict with the original intet of the constitution it has become nothing more than a paper tiger. This is a very serious problem.
Islam is a religionen claiming to be Gods final will and purpose for humanity. This sacred scripture contains within it certain rules. You have the same debate within this religious community of Islam about the interpretation of the rules you find within the quran. Progressives say that, for example, the practise of having multiple wifes must be seen in its historical context and should be abandoned by modern practisioners of the religion. On the other hand you have orthodox schoolars claiming that the Quran is the final word of God and therfore its rules applies for all eternity, hence a man may have four wifes at once.
This conflict between the need to sometimes reform a sacred text, whether it is a document such as the US constitution or a religious sacred text, is not easily dealt with. If you truly belives in progressivism whatever people right now think is right should be followed. On the other hand if you go for historical intent or everlasting divine rules, you also get stuck in a way with rules that are, to most, completly moronic. The US constituion can be ammended. But still, I think most libertarians and alot of conservatives have a mind-set involving a belief that the constitution contains at least a few principle and rights that are of an everlasting nature and should never be abondoned whatever the majority hold to be true at any given moment.
It is a very difficult question how to deal with this fact…