I have a cheap OTF - $39 - and it's no more worthless than a $25 folder. It cuts down boxes, or opens them, cleans fingernails, and does most of the other stuff an inexpensive knife does. I've had Branded knives that were problematic out of the box and a huge disappointment - like the Buck Strider Tarani in 420 and FRN. Bad lock, soft steel, overdone features, riveted construction, abrasive checkering that damaged jeans within a few days. In comparison the OTF is looking ok. Not the quality of a BM Rift or Strider SnG, no. Worthless? That's overreacting.
Form factor on blade steels, shape and grind do make a difference but a lot of it is also user skill. Changing up from the OTF to a BM CQC7 chisel grind tanto reminds me of how it steers to one side cutting and has no belly at all. The OTF I chose is a simple single edge blade grind with swedge with is about average on the market, and handles about average for the knives I own. So far it hasn't needed sharpening but I'm just using it EDC to see what will result.
PC factor is local. MO allows OTF daggers if you have a CCW permit. When and where to use it is entirely up to the discretion of the owner. I've been criticized for wearing a Buck sheath in an office environment during deer season - but the same individual had a 8" butcher knife in her purse to cut some going away cake later in the day. I suspect some of us can have a problem with ANY knife at all in some circumstances, you have to use brain matter and judgment. Why an officer would stop and frisk is related to what were you thinking? In MO not currently a major legal issue above and beyond any other knife. I realize YMMV and officer discretion is involved, but I've never been stopped and frisked in 63 years outside of MP training. Laws are rapidly changing and switchblades are not as heavily legislated as they once were.
I don't have self service issues with knives - and if they fall apart I don't blame the maker or send them back for service. I can sharpen one well enough, and writing to ask for a part seems to be supported by others who have done it. Working on my own cars and building AR's hasn't proven to be a deal stopper other than simple financial analysis - is it worth the repair cost yes/no? The last OTF I owned came to me heavily used, a cast Nato which broke some internal bit off. I tossed it - the same as I toss other disposable use items. You get what you pay for, and paying $300 for an exotic blade (which I have done) means being choosy and not getting yourself jammed into a corner. Blaming the tool for poor judgment isn't something I indulge in.
Dirt and crud can get into a open sided frame or liner lock much easier, and there is a lot of it out there. Pocket lint, food stuff, grit, sand, whatever - but for the most part I see credit cards torn up from it a lot more than my knives. It's called maintenance and you don't let your tools get that bad. Inspect them, flush them out, use the proper lubricants, etc. Interesting topic as there have been recent threads on assisted openers jammed shut from grit lately. A closed sided cast handle with the only port facing down would seem to be a better protection.
It also goes to getting fired in the pocket. An OTF requires you depress the cocking button fully down it's travel before it's released. Once free it is propelled by spring pressure and it can barely penetrate paper. If it does not lock open, and there is a pocket in the way in most cases, the blade floats in the handle and can move up and down. A folder can open from gravity alone if it has a bad detent or travels about as far as the button on an OTF, and if it's assisted or auto, has spring pressure forcing it open to lock. It might not make it that far but the blade is usually at some angle to the handle and one end is fixed - it's not floating. I've had folders open in my pocket and I would prefer the OTF as it's less a problem overall.
OTF's have advantages and disadvantages, folders have advantages and disadvantages. It's much the same as piston or DI and you sort out which package of features works best for you. It doesn't mean that one is inferior to the other, both have a place. What we have is a national policy of bias blanketing our use which was originally unfounded and meant as a test bed for political activism. It worked so well we saw a repeat and it eventually resulted in the AWB. Logical analysis of use and actual experience shows a lot of the public myth and misinformation about OTF's relates to a complete lack of familiarity - just the same as the AR15 as a sporting rifle.
We are going to see more OTF's and more users, I'm keeping an open mind about them. A nice AUS8A single edge 3.5" long with G10 handles for $80would be a good working knife. Nobody makes it in the current climate but when they do things are going to rapidly change.