Should you get travel insurance? The short answer is YES! I never leave home without it! I have a plan that covers me for trips of up to 30 days and is set to auto-renew every year, so I don't even have to think about it. I've never had to use it (knock on wood) but I am covered in case I need it!
No one wants to think that it will happen to them, but it COULD. Better to be prepared.
Don't forget - it's not always you that you have to be concerned about (thinking along the lines of 'I'm a great driver/skier/cycler etc etc), but everyone else around you! Just because you're an awesome driver doesn't mean that guy barreling down behind you going twice the speed limit is (for example).
Even just crossing the street can be dangerous - if you're in a city where they drive on the opposite side of the road than what you're used to you might forget that you need to look the opposite direction before you cross (going from North America to Australia or vice versa for example). Or in a place where pedestrians most definitely do NOT have the right of way and every time you step into the street you're taking your life in your hands (Vietnam for example).
I have an acquaintance who wound up having to borrow over $30,000 to cover his hospital bills after he got into a scooter accident overseas (& the hospital won't let you leave until you've paid!) - he had been told that hospitals in (Asia) are cheap and that even if something does happen you don't need insurance.
On the opposite extreme, another acquaintance got put up in what felt like a 5 star hotel room at a hospital in Switzerland when he busted his leg on the alps because he DID have great insurance.
Credit card insurance will cover some things but not others - READ your policy carefully.
Your work may provide some kind of travel insurance, but again, READ the policy.
Always check what the policy covers, and even more importantly: what it doesn't. You might be surprised at what is and isn't covered... and many don't cover "dangerous" activities (and each company has a different definition of what they consider dangerous).
I have not personally used World Nomads (because my plan is an auto-renew one that covers me for extended trips), but I've read that it provides some of the best travel insurance for short trips (less than a week to less than a couple of months). Plus they seem to cover more of the so-called "dangerous" activities that many other insurance companies do not. If you're gone longer than that you might want to look into extended trip coverage.
Get a quote here:
I think this article from Matthew Karston at 'Expert Vagabond' sums it up quite nicely: Should You Buy Travel Insurance or Not?
As he states, get the travel insurance "because sh*t happens!"