The Garmin Watches don't have DRAM for power reasons. The processor is a memory constrained microcontroller without a hardware memory management unit. Without the MMU you don't get as powerful memory virtualization or process isolation.
People with direct experience of the manufacturing sector in the US and abroad (including me) will certainly tell you that America's capabilities have deteriorated, at least relative to other countries. The machine tool industry is considered a good bellwether for industrial capacity and there's been some good research on this topic if you're interested: http://www.bismarckanalysis.com/Machine_Tools_Case_Study.pdf
I've looked at the financials of hearing aid companies before. And the short answer is that the money is not going to the hearing aid company. Of the $5k you spent on your hearing aid, the hearing aid company was probably paid $500, and the other $4.5k went to the audiologist.
The problem is that most consumers' revealed preference is for better performance rather than replaceability or device longevity (I know some people here will express a different preference, but you are a minority of consumers). Consumers don't factor device longevity into their purchase decisions, so companies don't prioritize it during the design process. And it needs to be prioritized because design decisions for longevity involve tradeoffs with other device performance metrics like size, weight, battery life (you can improve battery longevity by decreasing the depth of discharge of the battery before a recharge is required), processor performance, price.
Unfortunately this article clearly demonstrates the problems companies face when they try to improve longevity at the cost of performance. Apple implemented processor throttling based on measured battery condition to improve the longevity of their devices, but even in this article, seemingly focused on device longevity, they still receive criticism for this decision:
"But even consumers who hang onto their old iPhones for as long as possible learned in 2017 that Apple released a software update that slows down old phones to counteract aging lithium-ion battery problems."
I can't speak to the CC26xx series specifically, but normally deeply embedded cores running a ROM stack like that have some additional SRAM which can be loaded at boot for firmware patches.