What is wrong with folders? Seems like the best, if not only option for EDC.
Nothing wrong with folders, but they do sacrifice some things for their ability to fold. For example, design freedom. It's not feasible to produce a folder with the form factor and ergonomics of the Perrin Neck Bowie I linked earlier; folding something that thin is not doable. But for any folder design it is possible to make an equivalent fixed blade which has no mechanism to break or wear out, is more durable, weighs less, is easier to clean and maintain, and accumulates less dirt to begin with.
edit: sorry, I was unclear in my previous post. Didn't mean to imply that folders have no upside. Rather, their upsides are not very relevant/useful to me these days, therefore it's pointless for me to accept the downsides.
Many fixed blades are easy to EDC - just stick them in a pants pocket or jacket pocket. The Neck Bowie would disappear in a pocket better than my thinnest, most lightweight Spyderco folder. (Did you see the photo where the knife sits next to an iPhone?) When pocket carry is no good, there are all sorts of ways to keep a fixed blade handy. Attached to belt, clipped to waistband, on a neck chain, inside a wallet, anchored inside a shoulder bag, velcroed under a car dashboard. You can use several different sheathes for the same knife if necessary.
Also, why flat ground? Sounds liek you know a lot about knives. Tell us more, plese.
Just do stuff - open a cardboard box, spread butter on bread, slice a melon, cut an article of interest out of a newspaper, peel an apple. If you try any or all of these with a run-of-the-mill folder which has a thick blade and hollow grind, and with a run-of-the-mill kitchen knife which has a thin blade and flat grind, you'll probably notice some sort of difference. Not just in results but effort expended.
edit: also forgot to point out that fixed blades can have significant benefits over folders for self defense applications. A drawn and opened folder in a firm grip is pretty much as good as a fixed blade; folders' weakness is the (comparative) uncertainty of getting to that point.