Haven't seen a new lock that I feel will sell well to the masses. We don't have too many issues with frame/liner lock designs, so I'm not seeing a reason. All non-frame/liners we've utilized in the past have been losers.
It's unfortunate that alternative locks have not proved profitable for you guys in the past, perhaps it was the overall design that failed and not the type of lock. I think it's safe to say that other companies have proven alternative lock designs can be and are popular with the masses. The benefits are probably not appreciated by the average customer (the same thing could probably be said for blade steel differences, HT, G10 -vs- Carbon, subtle fit/finish differences, etc.) so it's probably does not impact overall sales much, but I can only assume they are profitable for the companies offering them or they'd discontinue them. I'd also concede they are not a feature that aggressively sells knives, or we'd see the liner/frame locks go away in favor of alternative locks.
IMO, fashion and performance don't always contradict each other. Feel it's more personal preference than anything else here. I'm unsure if its fair to label a specific build set up as fashion only.
I think a logical/scientific case could be made that some features are more functional and superior to others when it comes to a knife being used hard in a variety of conditions.......then again I'm a scientist so I'm predisposed to argue
An exposed frame lockbar is easier to accidentally release with any twisting motion with a firm grip. While not the norm, the reality is sometimes twisting happens while cutting especially in soft pliable materials or if you need to cut an arc. It's also not a left hand friendly design because the users grip naturally tries to release the lock bar. Now hopefully even if that happens the user is cutting safely and never causes an injury, but that doesn't mean it's not a quantifiable advantage. Even if you dismiss the posts about inconsistent lock bar tension, locks failing, lock rock, and detent holding power we read about daily (which I'd bet is restricted mostly to us knife nuts) I'd say it's beyond a personal preference issue.
The same is true for smooth handle slabs, while fine on a knife used under ideal conditions, if you work outdoors sooner or later your hands are going to be wet, sweaty, dirty, you want a knife handle that maintains that grip. Now some materials like micarta, wood, etc. can provide good grip when wet even smoothly finished. However metal and carbon fiber do NOT share that quality unless aggressively textured. Again I'd say that's a quantifiable advantage, unless you never run into those conditions, which I'm happy to admit most customers probably don't, and if they do they probably avoid them by leaving their $200+ knife in their pocket or at home.
I know nothing of the knife business, and no one can argue with ZT's success in that arena and my suspicion is that the above only impacts a tiny percentage of overall knife customers and hardcore knife enthusiasts are probably not a profitable group to cater your products/features to, but a handle that provides better grip in a wider range of environments, and a lock that is more secure under a wider range of cutting tasks and/or when being used with the left hand goes beyond just personal preference to me.