My apologies for not browsing the entire thread, but I have experienced similar issues to what certain people described. I purchased a 15” MacBook Pro (2016) in the early months of 2017. The machine had been running fine apart from the keyboard issues. Basically I noticed these right from the start, but perhaps they aggravated or I simply started paying even more attention to them later on.
Overall the keyboard and its keys (and even trackpad, or maybe I was just going berserk eventually) just kind of felt off in a way. It did not quite feel like a new and smooth keyboard. Additionally, the space bar seemed to have quite an issue, and the right half of it seemed way less responsive than the left half, as if it always kind of was partly stuck (despite it doing the trick purely practically speaking). Beside this, the arrow keys were quite the disaster from the start, especially the “up” and “down” arrows. Pressing them down was simply a hassle, it did not feel smooth and they just were very unpleasant to press down - requiring a strange amount of not very well distributed amount of pressure. The same thing applied to several other random keys on the keyboard. Beside that, there was the “high-pitched” noise issue, where usually certain keys specifically, would produce an annoying sound while being pressed. This did seem to be triggered by the machine being on a bit of a higher load. Overall I was not satisfied, and when the system got a bit hotter, the entire keyboard got less responsive - though still usable, just rather unpleasant - and produced this kind of “sticky” feeling, as if I spilled some sugary beverages on the keyboard, they had gotten mixed with some greasy crumbs as well and had been sitting there for years.
At one point I got so annoyed that I decided to bring it in for a repair, or whatever solution my local reseller could offer me. I was quite afraid, since I already owned this laptop for quite some months now and it was the first time reporting this problem to them, also thinking perhaps the reseller would either have me pay to get it fixed or brush it off as some cosmetic blemishes and no actual defects or perhaps act as if they were unaware of any similar cases and would be unable to reproduce these issues. Luckily, the guy from the repair service from the reseller told me he had seen similar issues before, even though he cautiously mentioned it as being only “a couple of these”.
About a week and a bit later I receive a message saying that my laptop was ready to be collected from the store again. Even though I did not agree to any repair costs, I would have to pay the costs to get my laptop tested on these issues and have them make an estimate concerning repair costs in case they thought my warranty does not cover the issue. Being broke and almost having to live under a bridge because I purchased this laptop, I almost did not want to visit my reseller anymore at that point in order to see what would be the result. I did pick it up though, as I needed my laptop back a.s.a.p., and I was immediately told that basically they had to replace the keyboard entirely. When I got home I soon noticed it was the revised keyboard; the problems seem to be gone (at least for now), the feeling of the entire keyboard is more tactile and less mushy and smoother, the “high-pitched” noises seem to be gone, space bar works great and the symbols and text changes on the “control” and “option” keys are there as well.
Now I read the form they gave me, and it said: “top case replaced”, and beneath this also when listing the parts: “top case with battery, iso, space gray”. I am not familiar with parts that much, so what do they exactly mean? What exactly did they replace? The trackpad and the entire top frame thingy as well, so not merely the keyboard itself? I never realized recent MacBook Pros were this much basically unibody, so to speak.
