Well, like many other things, better documentation increases cost. Assuming this error is nothing you as an end user can do anything about, beyond replacing hardware, I would suggest it's adequate for such a purpose. If fact, internal TAC documentation might be no more informative, i.e. tell customer hardware needs to be replaced.
Of course, issues like this error, likely go beyond TAC, as vendors usually want to mitigate a reoccurring issue.
Such mitigations might provide for later hardware revisions for the "same" part number. But how often do you see any documentation why hardware has been revised (when there's no spec change)?
There are other good reasons for "poor" public documentation including trying to keep proprietary info secret.
Heck, don't know if you've been in a similar situation, but I've worked in large companies, buying hardware from Cisco, where Cisco required NDAs, to discuss their roadmaps, and work with them on what the roadmap might be. As I've signed such NDAs I cannot be more specific. However, such practices aren't limited to dealing with Cisco.
I mention the foregoing because your "wish" is reasonable but there are various reasonable reasons it's unlikely to be met.
