You benefit from the mortgage insurance in the form of a lower interest rate.

Normally a person with a 10% downpayment would pay a higher interest rate than someone 20% downpayment.  In Canada though, with our mortgage insurance rules, the two pay the same interest rate (or the former pays a lower rate if this article is to be believed, though I'm not sure I buy it).

Besides, lots of insurance is for the benefit of others, eg. the biggest part of your car insurance is for liability purposes.