Others have commented here on what is the actual shame of this issue, Microsoft or not: forced obsolescence of hardware. Microsoft's history of "free" upgrades you've cited has no bearing on this situation since no new version of Windows will run on the obsolete hardware. It is a dreadful shame.

It’s fascinating that some people see Windows as a retail product who’s customer is the end user.

It’s much more accurately described as a foothold for all the other products. From Office and Sharepoint to the multi-figure licenses on the big business products, it’s all resting on the fact that Windows is used by future employees who then become managers who then become C-levels.

Seeing it through the lens of the product for consumers, free security updates can be MS giving a gift to the original purchasers. But seen through the lens of a foothold the free updates are a marketing expense so that maintainers of legacy systems have just enough reason to backburner investigating non-Windows operating systems as replacements.