I have one of Lofty based kits, same as on the DVD he did which I also have and enjoy. It lives wrapped in a plastic bag (seemed sensible addition as water collector) in the small inner pocket of my main coat. Next to my gloves (nirolex) and silver blanket. Day I got it I stripped it out, added a few extra items and made sure I was comfortable with what was in there.
Ok so the gloves and blanket have seen more action than the tin, RTA's (or whatever they call them now) and various other messy situations I seem to arrive first on scene at. Small first aid kit has pretty much dried up as an every day carry, I use my hands and gloves for anything serious, and have a couple of plasters for everything else. However the tin does add a layer of security (not to mention said plasters) and my main car kit not normally far away.
I don't smoke, so no lighter day to day. I don't have a every day carry knife (although considering one), only things always with me at the moment are my keys (with torch, 99p from tesco and excellent) and my coat with its little pack.
Why would I need it? Well for survival not yet, but as Lofty says in his DVD the sewing kit saved me more than once. I was stuck for 5 hours underground coming home from the office when the tube died and the torch was a great morale booster as the battery lights started to die on the train. Its just snowed, and peeps got stuck in cars all over the place. Yes you should have all sorts of toys in your 'car kit', but when travelling with a business colleague they may not be prepared. Then the ability to get a fire going may well save your life.
Even in the walking scenario, fall down a hillside and break something. Mobile if its working, great. However the whistle will attract attention and guide peeps in, even the fire starting stuff may help you make a smoke signal with what's around you, and the lid is your heliograph. As the heli guy said, phone is great if you can describe your location, otherwise you need to stand out somehow.
Yes is pointless when you have your big car kit, you pack with all your toys, the weathers good, and you have planned properly. I think the time it will save you is when you are not expecting it to go wrong, you forgot your mobile, it was just a quick walk on the moors, the weather changed, you fell.
Hindsight is great, and you can kick yourself at all the mistakes you made to get where you now are. I am sure there will be more than one, and at least one totally unfair thing that's happened. That's the time when that small pocket kit will save you, so hopefully you will never need it, but while its light, small, and I dont notice the weight in my jacket its staying, even in the UK with our feeling it cant "really" go wrong.