[quote name]a chair becomes a stool when you cut the back off[/quote]
What about legs? How many legs does your stool have? (stop giggling at the back!)
The point is, and we all tend to forget this, is that these words (racer, tourer, etc) have quite particular meanings to the individual. This can result in confusion sometimes. We think we're talking about the same thing when in reality there are differences; sometimes so slight as to make little or no difference in a given context, but differences none-the-less.
I don't think it's over thinking it at all, it's being aware of differences and their potential for confusion. For instance, the term 'race bred' is not one I'd use nor am I really familiar with. I have to more-or-less interpret it into something I understand... and in so doing have probably a completely different mental picture of a 'race bred' bike to the one intended! Whether that matters or not is, as I said, down to context.
The word 'racer' will remain as long as there are people (like myself) that continue to use it. (They're still Marathons btw, not Snickers!) The increasing difficulty for people like myself is that the word's meaning changes (as do all meanings; how many people are 'gay' as in happy these days? Your ageing aunt perhaps) and we have to become increasingly 'bi-lingual'. That is, you recognise the word has taken on a different meaning but you still understand the word in it's different context, no? Wicked!