While the benefits of safety equipment are clearly compelling, the "down sides" are equally obvious
Sure, but if you're going to take it that far then you have weigh that against all the other potential costs. For the tractor manufacturer, not putting an obvious, simple, basic and proven safety feature (like a ROPS) on a tractor is going to cost them a lot more in liability suits that the cost of manufacture. Liability losses will be felt in the pockets of the consumer just as mush as raw materials and labor. For the consumer, the cost of these features is far less than the loss of life or limb. So the "obvious" isn't so obvious. And why should we, or anyone else, expect any "form of refuge" for free?
And, the cost of manufacture is pretty low, and for any informed consumer those things are expected to be on the tractor. You don't have 'em then we don't buy 'em. Once again, that makes the cost a wash.
As far as repair costs: trivial to the point of insignificance. Now, sure as heck someone is going to pipe up with some $10,000 repair on a safety feature but, 1) it isn't common and 2) at least on my tractor all the features mentioned above are extraordinarily simple and easy to fix.
So once again, even when you go beyond the "obvious" the downsides remain trivial compared to the alternatives.
And don't get me wrong, I'm sure there are poorly implemented safety features out there. I'm not making excuses for those. Poor quality and design is poor quality and design regardless of the system.