In essence you're correct; a lot of constitutions were written a long time ago, and while at the time they were considered incredibly progressive, they haven't aged well (I'm thinking of the US constitution here).

I want to say I'm all for the ability to update the constitution, but with the way society is headed these days, it would be a regression; it would draw more power to individuals, it would reduce people's rights, etc. That's my fear anyway, I can't say for sure whether that will be the case.