I've got one.
They're super cheap insurance. 200-400 bucks/year or so for a 1-3 million policy.
People are so sue happy these days, I'm willing to pay a tiny premium to make sure I don't lose everything I've built up.
Imagine someone falling on one of your properties and you getting sued for a million, and suddenly you're cleaned out. No thanks. Especially if you have many rentals, it increases the odds quite a bit.
(And I say this as a person not a fan of insurance in general - in fact, if I lived in one of the states where I could get away with no car insurance by posting a bond, like California, I would.. but don't tell I.P., cause we differ on that. I would, however, be self insuring and pay any debts that are my fault.)
YMMV.