What about the disenfranchisement of citizens who's will is overrun by people not eligible to vote? Are you really trying to convince me that we should make our elections insecure because some people want to vote in federal election while simultaneously not wanting the federal government to have their ID. You do realize you have to register to vote right? Why should we all make our election insecure for people who don't even trust the government themselves?
Because its a free country, because a federal ID disenfranchises those who will find it difficult or impossible to get such an ID, because not trusting the government is the whole point of the US constitution.