Can withdraw if:
permanently disabled
non-reimbursed medical expenses for serious injury/illness
college costs
1st time home purchase
paying health insurance premiums if out of work longer than 12 weeks
the bottom line is some life agents make IRAs out to be investment vehicles "you can't access until retirement" when in reality there are many ways to access they money when you need it.
In general you can't. There are exceptions as you pointed out. Outside of the home purchase and college costs though tragedy has to occur. Qualified money can't be used to take advantage of a positive situation.
My point of course isn't that life insurance is the end all, rather it is one tool of many that has unique advantages other tools don't have. And if you simply dismiss life insurance you are failing to recognize those advantages.