I think the idea of the dots is to keep the protector slightly raised up away from the glass of the phone screen itself. That maintains a gap large enough to prevent the interference patterns (looks like that oil-on-water rainbow sheen) that you get when a glass cover is spaced just right such that the gap is some fraction of a wavelength of the light colors in question.
I have a Zagg, and it gets that rainbow effect. I don't mind it, it's subtle and doesn't bother me. I can't see it when the phone is turned on and shining up through the layers.
My wife and I both got Zaggs installed by the ATT folks when we got our phones last Sept. Her protector broke when she dropped it face down onto pavement a few weeks ago. It must have struck a pebble sticking up enough that the gap provided by the edge of the case wasn't enough. And that's to be expected. Only if your phone falls into a perfectly clean and perfectly flat floor will the gap from a typical case keep the face of the phone safe.
Anyhow, her zagg broke and came off, but the phone is perfect. I replaced hers with one I found on Amazon that does have the dots. She likes it just fine. There is no way to know if the Zagg prevented her phone face from cracking or shattering. It's all speculation. But it probably at least prevented a bad ding/scratch at the point(s) of impact against the gravel or whatever was on the ground. So it is likely that the screen protector paid for itself.
A couple of weeks later, my note 8 slipped down a crack between the butt cushion and arm rest side of the recliner I was in. I didn't notice it. This is an electric recliner. As I lowered the footrest, I heard a loud pop, and reversed the mechanism. I rooted around and found my note 8 in the works and fished it out. It had a tiny pit in the corner of the Zagg. A few days later, a crack appeared and then spread larger and larger so I took it off completely. I later found a protector at Sam's Club and just bought it. It is another Zagg. I have it on now.
Again, there is no way to conclusively say that the protector saved my phone. But I suspect it did, if only by breaking loudly enough to make me stop lowering the recliner in time!
Had that been the phone's screen, IT would have been what needed to "pop" before I stopped the mechanism.
Both of these protectors came with extensive cleaning supplies and instructions as well as alignment jigs to get the screens on properly. I did both installations very carefully, and they both look and have stayed attached fine.
The curved edges of these Note 8 screens don't work well with a tough case because I can't get my finger down into the crevices at the sides to touch those edges. I don't think these screen protectors make much difference. Maybe if you didn't have these big cases on, you would notice a sensitivity difference along those edges. But the Pelican cases we're using make the curved edges a pain anyhow, so we don't notice any effect from the screen protectors.
With all of the protectors we are using, the touch response of the screens over their non-curved surfaces seems fine, and the S-Pens work fine, too.
Naked is nicer for sure. But I think my protectors have paid for themselves on both of our Note 8s, as have the rugged cases we're using. Yes, it all makes the phones bigger and clunkier. But I just want the units to operate well and last a long time. We both had S2s at the time we upgraded to these Note 8s. So you can guess how long we tend to keep these phones! And both of our S2s were and are in excellent condition. We had Otterboxes and screen protectors on those phones the whole time, too.
So as much as I do prefer the size and feel of these phones naked, I'm not willing to risk going commando. To me, the touch sensitivity seems great even with these protectors. The short times (about a week for each of us) we both were without our protectors didn't make either of us want to continue running naked.