Moras are effective knives used by working people all over the world. The are inexpensive, light, sharp, good ergonomics, and they work.
There is a school of survival and bushcraft that says you need to go out with some sort of short sword to be safe in the woods. That is a lot of BS, IMHO. If you are in the jungle, a machete makes a lot of sense. Hunters have a need for butchering tools. Other than that, if you are on foot and in the north temperate forests, a mora and an SAK will take care of your needs well. I do carry a wire saw, but mostly because they are light, cheap, and take so little room in my PSK.
First misconception: you should fear nature. That's a bunch of hooey dating back to the Pilgrims. We are modern people and should be free of such superstitions. We should understand natural forces and be prepared to deal with them. The equipment is inexpensive and the knowledge is easily accessed.
Scenario one: You head out in the woods and you get yourself lost. First of all, you shouldn't let that happen. We have the best maps ever created and good compasses are as cheap as they ever have been. You can buy a very effective GPS with all of North America mapped on it for $79. You can learn to triangulate with a compass in an afternoon. So, you managed to bypass all that and you got yourself lost. In following your backup plan, you left your destination and a deadline with a trusted friend or family member. You might have checked in with a local ranger station too. So you plunk your butt down, reach into your pack, pull out you essentials and get comfortable until your backup plan kicks in an they come looking for you. You have at least minimal shelter, extra food, water, firestarting materials and signalling devices. In any kind of forest you can gather enough firewood to keep you warm. You don't even need a knife in this scenario, but an SAK would be plenty and a mora would be more than enough-- you could cut small branches to break off.
Second scenario: you aren't lost, but you fall and injure yourself. All the backups and preparation from scenario two kick in. You may not be able to stand or walk, so I don't know what a big knife is going to do for you. If you can walk, you aren't injured that bad and it's time to go home. You go to your essentials and get comfy and wait for the backup plan to kick in. If you are really tough and a short distance, you migh be able to crawl to a main trial crossroads or trailhead. Good luck.
Scenario three: you lose your gear crossing a stream, a bear hauls it off, or a two legged snake steals it. Now you're in deep doo-doo. You still have you backup plan. You are healthy and uninjured. Hopefully you have the following goodies on your person: mora, SAK, compass, whistle, firestarter. If you did your homework, you know where you are, so the compass is just good backup. There are few places in the continental US where you are going to be more than three days out. You lost your gear, so you sure don't have much load. You can cover 40+ miles per day with no load and in reasonable shape. So you might have to spend a night or two in the woods. You build a shelter appropriate to the weather and make it through a cold night or two. You can get by without food for a couple days, but you might find berries in season and your small knives will clean any game you might club or spear with a stick. You can certainly build a fire and stay warm. You're going to have to risk drinking water without treatment, but all the big knives in the world aren't going to change that. In fact, if you are that far out in the weeds, the chances of the water being bad are small. If you are out on a long trail like the Pacific Crest Trail, you are going to run into someone in a couple days anyway and a coule days travel on most sections would bring you to a point where you could get help anyway.
So, the only real benefit to having a big knife, hatchet or machete, would be to build a shelter and chop more firewood for one or two nights-- if you are healthy enough to be able to weild one. IMHO, you would be be better off to carry an equivalent weight of survival gear rather than a big knife. Being isolated from your gear is the worst scenario, so what you carry on your person is what you will really need. A wire saw in that kit will build your short term shelters just fine.
And, there's one other thing about the big knife idea that wrankles me. We need to go out and enjoy the wilds without tearing it up. Leave no trace is the way to go. You need to take your own shelter and use a stove. Campfires are fun, but they need to be restricted to high-use campgrounds where they are safe and the mess can be managed. A folding saw is a good compromise, safer to use, and is still lighter and much more expensive than a big Rambo blade.
So with all that in mind, not only is a mora a useable tool, but it is the best alternative-- you can afford to have one in all your survival kits and it is a very reasonable tool for its weight while hiking.
[exit soapbox mode; return to normal programming]
So it became a tradition, people just like to chop wood, it's probably in our DNA from the last half-million years. :thumbup: 
