I keep several around. You make a very valid point; if you're going to carry a firearm then a first aid kit is just as, if not more, important than a spare mag. I think that here is a good place to note that if you are traipsing around the woods or brush constantly then a survival pack is also a necessity. If you are alone and injured there is no guarantee that you will be able to make it out under your own power. You may be able to bandage a wound, but, are you able to survive long enough to make that first aid worthwhile? Safety is the key point.
"Those who hammer their guns into plow shears will become subject to those who do not."