I guess this is tangential to the thread, but I couldn't resist.
The 2A purpose is quite clear; a free state is less apt to become a totalitarian state with an armed populous. Step one of establishing a totalitarian state is to disarm the people. Our founders knew quite well what made it possible for them to escape the colonial rule of the British crown.
Totalitarianism, in particular, hadn't been invented at the time that the constitution had been written (FWIW, the fascists had armed militias that they were quite fond of. So militias can also be a source of totalitarianism as much as liberty).
If anything, the Whiskey Rebellion and the War of 1812 showed that expectations for the militia were rather overblown. The government adapted and moved on all without having to repeal the second amendment. I would argue that people that try to put that same trust in a militia today, could learn from history.
That Patriots were a well regulated militia, capable of resisting oppression on the governmental level. I don't see any such thing today. The militia, as intended by the framers, does not exist anymore. If you want an originalists interpretation, then it seems like gun ownership should be limited to white males between the ages of 18-45ish (as defined a few years later in 1792). I think that's probably how they saw the militia. I doubt they wanted to arm the slaves (or apparently even the free black men who fought in the revolution), the old, the handicapped or white women for that matter.
One the one hand, I think that the writers of the constitution got a lot of things right, but I reject any attempt to canonize them as somehow unusually prescient about the issues of our day. They acknowledged and abetted slavery with the three fifths compromise. They thought our state legislatures should elect our senators for us. Made no effort to protect the right to vote: allowing states to discriminate based on race, sex, ect...
To ensure that only eligible citizens vote requires knowing who is (or is not) one of them. The easier that it is to establish that then the greater the chance of one doing that multiple times. It takes but a single "extra" vote to cancel (or double) mine.
Once again, I sympathize, but at this point, it looks more like solution looking for a problem. Think of it this way, how many citizens will lose the ability to vote versus how many acts of fraud were prevented? Not everyone lacking a photo id is a non-citizen. In fact, of the people actually trying to vote, I would argue that the vast majority of them are not non-citizens.