So that you don't have to pay $15.00 for repairs when other manufacturers require you to pay $0.00 for repairs and replacements?
Paying double the reasonable price for a product, just to get a lifetime warranty, isn't very economically sound. Especially for electronics, which you'll want to upgrade in a few years anyway.
Besides, companies come and go. I've got a few 4sevens lights with nice 10 year warranties. Yeah, that didn't work out so well.
Surfire might make nice products, but they're priced for military and law enforcement contracts. Government doesn't care about the price, nor the cost of disposable batteries.
Zebralight is still fairly expensive, but it's a reasonable consumer price for what you get.
Would I use a Zebra for a life & death situation? No. But I wouldn't use a Surefire, either. I'd have at least 2 lights. With a backup (or two), the difference in reliability between 99.99% and 99.999% isn't really relevant. Two lights of good quality are never going to both randomly fail at the same time.