I'm pretty sure they wrote "3rd generation" for 32/64 but didn't write anything for the 8GB
Your recollection of history pretty much agrees with mine.
In fact, I recall the reverse misconception being commonplace at the time:
Many observers said that the improvements made to the 32GB and 64GB models weren't significant enough to justify them being called 3rd generation devices. There was significant resistance, at first, to using the expression "3rd generation" to describe the updated 32GB model and new 64GB model on Wikipedia. (The main reason for this argument was that there was no major cosmetic change to accompany the internal upgrades.) There was a pretty vocal minority who argued that the improved 32GB and 64GB models
might have deserved the designation "2.5 Generation", or maybe "2GS", or something along those lines -- but certainly not "3rd Generation".
After reviewing the presentation Steve Jobs made when the 3rd generation iPod touch was announced, I was already perfectly satisfied to agree that the 32 GB and 64GB models constituted a 3rd generation iPod touch, whereas the 8GB model was still the same product as the existing 2nd generation device.
As I recall, the issue wasn't really finally put to rest until the following year when Apple announced the successor iPod touch (the current model -- the one with Facetime cameras), and officially called it a "4th generation iPod touch".
Anyway, right from the start, Apple's literature was careful to distinguish the 8GB model from the 32GB and 64GB models, with some extra features (such as improved Voice Over features for the visually impaired) being available only for the 32GB and 64GB models but not for the 8GB model. Since there was always a disparity in the availability of features for the 8GB model versus the 32GB and 64GB models, it stands to reason to me that there should not have been any expectation that feature parity would be established or expanded in any future firmware updates.
To the OP: Regardless of what name you chose to use to describe the 8GB models sold after the introduction of upgraded 32GB and 64GB models, I don't think your argument holds up to a reasonable level of scrutiny.