Great topic CJ. Love discussions like this.
Allow me some rambling....
Mark - I think there are alternate definitions of the term 'style' that don't relate to current vogue, but more technique or historically oriented -- per Merriam Webster: "a particular manner or technique by which something is done, created, or performed (e.g. a unique style of horseback riding, the classical style of dance)
CJ - I would say that I certainly understand, and am sympathetic to, the sentiment expressed by your friend, in that we should be careful about losing historical perspective on the origins of these flies. However, I would qualify that by saying that is being done is classifying the style of fly as opposed to renaming the pattern. Or qualifying the way in which a particular pattern is being presented. A Parmachene Belle may be tied in a variety of styles. Only one style may represent the 'original' fly pattern, but over time these patterns can, and often are, tied in other styles as well. Some patterns have migrated from large winged, blind eye wets, to smaller down eye ('Bergman') wets, to streamers, bucktails, etc. This variety of forms makes the use of a clarifying tag appealing. If I said I was tying a Hare's Ear and left it at that, would you know whether I meant nymph or wetfly?
Unfortunately, taking a extreme hard line on this would mean that if one were to tie a Parmachene Belle, then it would have to be a blind eye wet, and that one using the same color scheme tied in small, down eye wet fashion (a la Bergman's Trout) or streamer would need to use a different name altogether. Hardly practical and likely much more damaging over time to the history of the original pattern. I know that Henry Wells created the Parmachene Belle, regardless of what form or forms it is tied in today. Like it or not, because these older patterns have migrated across fly styles, the tags are almost a necessity at this point. The danger is that along the way someone may mistakenly think the Parmachene Belle was originated by Bergman or Mary O. Hopefully, there is enough reference material out there that if someone wanted to really know the origins of a particular pattern instead of making blind assumptions, he or she could do so relatively easily.
Of course, these style 'nicknames' have been the product of the popular landmark books that brought them to the forefront. The fact that these books contained comprehensive collections of these patterns in a singular style (for the most part) and the books' widespread ownership are what make the particular 'nickname' choices natural and logical. This was no doubt driven home in the minds of current tyers more recently through Schmookler's "Forgotten Flies', which featured both Mary O and Bergman in significant fashion.
The unfortunate byproduct of all this is that it may help muddy the fly history more than time already has. However, at this point it seems a necessary evil. I always revert back to Carrie Stevens Gray Ghost as the classic example of this. It would be hard to argue that a fly tied with the exact same materials as a Gray Ghost, no mattern what form it takes, is not a Gray Ghost - because the pattern elements/colors are the same. That doesn't necessarily make it a historically accurate representation of the original, however. This is the exact reason people tend to qualify Mrs. Stevens style with terms like Rangeley Style or Stevens Style - for clarity as to how the fly is dressed. The difference here is that the style originator and pattern originator are one in the same.
Anyway, like you said, good food for thought. Sorry if I droned and got a little repetitive here, as some of my thoughts echo others here.