The argument isn't "If it isn't broke, don't fix it". It's that not all change is necessary (or even good). If something is clearly broken, by all means fix it. If it's not, then things get more complicated. Maybe a change is still in order (but maybe it's broken in a non-obvious way, like the Razr in a smart-phone world). The idea that change is always good and always a sign of progress is absolutely false.