Yeah I saw that a lot in like the 2000s, when every time Canon released a non-IS lens, every single review would be forehead-slapping, OMG why didn't Canon think to make this IS? As if Canon would forget that IS was even possible, and it's something you could bolt on to anything as simply as putting feet on the focusing scale.
(The answer clearly is that on many lenses it'd be impossible, or make the lens twice the weight and/or size and impossible to sell.)
This too is surely happening at times. As a lifelong software engineer I just cannot see a reason the R lacks two memory slots or a larger battery, other than they're dumbing it down a bit to make room above for a "pro" model with higher margin.
The main reason that I promote as far as backup protection is concerned is the ability to use a wireless format to copy the captures in real time to a backup device. I can't see it being too difficult to have a simple Bluetooth or Wi-Fi connection to a compatible wireless thumbdrive or wireless dongle that can easily be written to just by being in the vicinity of the camera body. That would solve the problem of having to add the bulk and extra room necessary to make the camera capable of a trusted backup, without having the extra card slot. A confirmation window in the display would allow the user to see if the backup connection is working or not, and you could easily take extra precautionary steps to make sure that the copying is successful in real time. I don't want to contradict myself, and be hypocritical as to the next part of my reply by simply assuming this wireless feature would be easily accomplished by the engineers, as I know for a fact that it can, and has been done already. They just need to perfect the technology and make it a universal feature with the ISO community.
As far as the first part of your reply, I am with you on that example. There is a group of folks who act as though the engineers can just snap their fingers to get certain features added to a camera body without knowing anything at all about the background of the process involved in that addition. It just seems that everyone has a penchant for "Off the cuff" engineering solutions with absolutely no knowledge of what's involved in adding these most wanted features. I see it all the time with trusted reviewers even. Some are more consistent than others, but when a reviewer starts to demote a new camera body's overall score because they figure that the manufacturer left out "Something so simple".
A lot of fuss has been made about 4K technology (mostly the lack thereof) in the modern DSLR discussions, and I see that being a problem that Canon made for themselves with the advent of the video capabilities in the 5D MkII. It was a great feature, there's no doubt about it, but the sudden craze to expect top notch video codecs to be implemented into
ALL of the new models sullied the pool of comments for every single camera that didn't offer some kind of cutting edge video capabilities with every single model. Some people are to the point where they will literally destroy the review of a new DSLR, just because it doesn't have bleeding edge 4K video capabilities. I am of the school that believes in buying a DSLR to take still captures, and I am not invested in the video capabilities. I would like to see a "Stills only" model where I don't have to pay for technology that I am not interested in at all, as that is what a DSLR is supposed to be for.