Good comment from Day Tripper posted on the original Repacking post that I think has some excellent discussion points:
I try to clean out and repack my stuff every couple of months. Different seasons bring different needs. Plus when it comes to EDC stuff, if I haven't used an item in a few months it probably doesn't need to be in there anyway. I used to carry around a full fire starting kit complete with tinder in my EDC but never used it. Eventually it slimmed down to now being just a Bic lighter, magnesium rod for backup, and my boo boo kit has hand sanitizer (fuel) and plenty of bandage stuff (tender) that could be improvised if needed. In many years of carrying my EDC bag to and from work I can confidently say that I've never had to start a fire, build a shelter, boil water, trap food, etc. That being said, I seem to become much more equipped and redundant when hiking in the woods.
I do the same thing with reducing unused items - if it doesn't get used, it is up for removal.
Part of the challenge, though, is balancing the oft used daily items with the "I hope I never need this" disaster/emergency stuff.
Personally, if it is a "just in case" emergency item, really, it's probably not going to get used, so I am especially conscientious of the weight and bulk. I look to balance the likelihood of needing the item and the consequences of not having the item on hand when needed with the size/weight penalty for adding it to my pack.
Fire is one of those largely "emergency" capabilities--I need a lighter for the occasional melting of paracord ends and not much else. I unfortunately spend most of my time trapped within suburbia, so the consequences of not having fire starting gear, even in a disaster, would be fairly minimal. But, simple fire starting gear is compact enough and important enough that I make sure to have some. My EDC bag has a regular sized Bic and a pocket survival kit that, amongst other things, contains a mini Bic, a small fire steel and some TinderQuik.
And, as you noted, many of the bag's other contents could be used for fire starting. Gauze in the blow out kit, hand sanitizer, alcohol-based lens cleaner, alcohol swabs, travel pack of kleenex, 100% cotton shemagh and so on. Lots of options.
Another example: water filtration is another one of those capabilities that I'm really only going to need in a bad situation. Again, I run light there--a 1 ounce water filtration straw and some chlorine dioxide tablets. Less than 2 ounces total and takes up very minimal bulk. Probably won't be needed, but a capability that I want to have none-the-less, so I ensure that it's light, compact and doesn't really get in the way.
My Blow Out/Gunshot Wound kit is the same way--I sure do not plan to every need a tourniquet, Combat Gauze and so on, but it doesn't weigh much, and if I really needed it, I would not want to be without it.
So, while some of the gear in my daily carry bag doesn't see a lot of use, if it performs a critical enough task and isn't too bulky, I make sure to include it where I can. Certainly, evaluate your situation and your potential scenarios and tailor as you see fit.
What "emergency-only" gear do you carry in your daily carry gear? How conscientious are you about the size/weight of said gear? Has it ever saved your bacon from trouble?