I think many makers are unaware, or just becoming aware, of the reliability problems liner locks can have. Given that the recognition has been slow in coming, there's been little reason to go to integral locks. Provided you think liner locks are reliable, they also have the advantages of being relatively inexpensive to make, capable of being made easily by even a small-time maker, smooth, and allowing many handle configurations. And of course, if you look at strength, a good liner lock is plenty strong.
By contrast, an integral lock put some constraints on what the maker can do with the handles, and depending on your aesthetic sensibilities, can mar the aesthetics. I believe they're also more difficult to make, requiring accurate cutting of pretty thick titanium.
I think the integral lock is brilliant in its simplicity, strength, and reliability, and have no aesthetic concerns, so of course I hope more makers move to it. And they typically aren't defeated by white knuckling, torquing, spine-whacking.
Big Dave: don't want to talk you of anything, but just clarify one thing. You state "they may not be the strongest locking mechanism", as if strength is the most important concern about liner locks. In my mind, liner lock strength is not -- and has never been -- an issue. I'm beginning to sound like a broken record, but I think it's important to be clear: the issue that just about everyone brings up about liner locks is reliability, not strength. The axis lock, rolling lock, and integral lock may or may not be stronger than a liner lock, but so far they all seem much more reliable. Speaking as someone who cares about his fingers, that's important to me
Joe