I've thought on a few occasions about making a really sturdy spear and finding a remote place to try and kill a deer with it. I've certainly been successful at getting close enough. Heck, about 6 years ago I got close enough to touch a wild fawn, although it was just a fawn and they're not as attentive as older deer. And this year I got within 3 yards of another fawn, close enough to jump out and slap it before it could run away. I could easily have speared it.
One aspect of using a longer range weapon to kill an animal is that you don't have to watch what happens between the impact of your projectile and when the animal finally stops moving. When you take a hunter safety, or hunter "education", class, they generally recommend that you stay where you were when you made the shot for at least 30 minutes before you try to find the animal. They recommend this to prevent an animal from running further than it normally would before expiring so that it's easier to find, but I think it serves a double purpose. I think another important reason they recommend this is to protect hunters who still have some semblance of a soul from having to watch an animal die.
When I shot my deer this past fall I saw it fall within 10 feet of where I'd shot it. So rather than waiting I hustled down from the cliff I was perched on to tag my deer. I got down to it in about five minutes and still got to watch a couple minutes worth of agonized writhing before the deer went still. Before this experience I had this idealized vision that a deer gets shot and just plops down dead. NOT! Even when you shoot a deer with a rifle and hit the vitals, unless you get the perfect shot the animal suffers for at least a couple minutes and often several minutes before it finally goes still. While watching the deer writhe part of me wanted to load another cartridge and end its suffering with a close-range head shot, but I was carrying a 0.308 so if I did that I could well have blown its head wide open. Maybe next year I'll carry a 0.22 pistol with me during rifle season, although they don't let us carry firearms into the woods during archery season here in Vermont.
Perhaps it sounds strange, but being able to experience the above is a large part of the reason why I choose to hunt. It's painful to participate in the process of killing an animal (unless you've successfully buried your soul beneath years of modern pragmatism), but I think it's important to go through that if you're going to eat meat. I think it's easy for people to glorify meat eating when they're able to slough the duty of killing onto someone else and just get the end product. When the duty of killing is on your own shoulders, the whole process is far more demanding and powerful, at least for me.
I think I read on this thread about someone who wanted to eat liver and kidneys of a fresh kill right after field dressing. By the time I got to field dressing after having shot the deer and watched it die I was in tears and I didn't eat anything for three days. Not because I was grossed out, as I've butchered deer before and butchering mine wasn't any different, but just because the process of putting a living, breathing, walking, browsing animal in the crosshairs of my rifle and then intentionally making it dead was a very powerful experience. I hope that it never becomes any less powerful, and while I will certainly continue to eat meat my desire to abandon omnivory in favor of carnivory has certainly been tempered.