Why would you want to start taking a pension from your super before you retire?
One reason may be that you want to ease into retirement by working part-time and the pension can be used to supplement your salary income.
If you reduce your employment to part-time work, you may find you have insufficient money to meet your living expenses.
In this instance you could start a non-commutable account based income stream to help supplement the short-fall in your income.
One important point to consider is that you may be drawing down on your super earlier than expected, so this may have long term consequences, such as reducing your balance earlier than anticipated in retirement.
As earnings on transition to retirement pensions (accumulation phase) are now subject to 15% tax, depending on your circumstances, there can be an incentive for tax purposes to salary-sacrifice part of your employment income into super and subsequently withdraw it from the pension in the form of income payments.