Obviously, having 25x what you need, you should be able to retire tomorrow. I was in a similar position, but had not really put my savings in the right places to earn enough to retire. But, once/if you have them there, then why not?
Super is just a tax advantaged vehicle for almost any type of investment. As a result, you can reach your nest egg goals faster with it. You can put money into super after you are retired until you are 65, and can use it to reduce your tax (claim it as a pre-tax contribution) and to build money more quickly because of the tax breaks. Once you start to take money out of super by putting some or all of it into pension phase, the amount that is in pension phase must be withdrawn at a certain rate, depending upon your age. You can currently put $180,000 (I think) a year into super AFTER tax, as well as about $30,000 before tax (you can check the figures).
You are running no risks if you have nothing in super - just missing out on the tax breaks if you are on an average or more income. If you are on a low income, you might be better off. When you sell stuff in pension phase in super, it doesn't get CGT, but that may change. And the income you get from super in pension phase is not taxed (but that might change too).
Since these things are due to change in May, and you are self employed (so your boss doesn't put in the 9.5%) I would put some amount into super prior to that this year (perhaps the highest amount you can pre-tax, from what you pay yourself), in case they grandfather the contributions made before any changes. After that, I would review the changes, and see if they make any sense to your situation.