The $500k lifetime non-concessional cap (which if you had already exceeded before budget night will not require you to remove the excess) is designed to stop people churning money through their super accounts to minimise tax.
With the current non-concessional contribution rules ($180k contribution each year or bring forward three years for $540k) people can withdraw funds from super and re-contribute them. See any super financial advisor (before the 2016 budget) and this 're-contribution strategy' would probably have been recommended to you if you can already access your super and you are not yet retired.
It enables you to convert concessional contributions (i.e. paid in by employers and salary sacrifice) into non-concessional contributions.
Pulling money in and out of super (and paying your advisor a fee for the privilege) doesn't increase the funds you have to access in retirement. What it does do is reduce the tax your children will pay when they inherit whatever money is left in your super account when you die. Financial advisors hate this change because it means their 'copy-paste' super advice to clients will now need to be more individually tailored and the gravy train fees from this advice has disappeared.
