I heat up my computer quite a bit, Zbrush brings the CPU to the max, I also play Diablo 3 for hours and it gets as hot as it can. No issues, no high pitch (and I know how it sounds, when I first got my MBP, a few keys were high pitched for a few days before settling in).
Also, no issues with another 2016 MBP we have at work and no issues with my friends MBP - so I guess you just know a lot of unlucky people. I know this seems frustrating to you, but you have to try and be objective. And I know how our minds play tricks - if I ran into 5 or 6 MBPs with keyboard issues, I would also be convinced it's a flaw, and yet, even with all the people here - objectively - it's a small minority of people with issues.
Shims, if they exist, are probably a quick solution for people that have these issues. I can't say from experience, because in the region (Serbia, Croatia, Hungary, etc.) when you have keyboard issues, a new top is always replaced, individual keys are never fixed - so I have no idea what they do in the States and if they really install these, or is it just some placebo they do to calm people who replace 4 Macbooks in a row because they think they are not 'perfect' (Most of the stories here are that Apple claims it's working as intended, the customer "knows better", then they say alright, we'll do.... "something" - shims, whatever - and then the customer again thinks it doesn't work as it should - it's all a bit too 1st world to me, to be honest)
No, it's not a premature product, in fact, they released it later than expected. It was, what, 400 or more days?
As for symbol keys, they have been around on EU keyboards for a while now. I guess Apple decided to add them to US models which is, I think, a good move since macOS uses them in menus to display kbd shortcuts.