Agreed that the definitions and the flight time classifications really only have significance for airman certification, and perhaps for hiring at an entry level. If you were involved in hiring at an airline which is typically hiring GA pilots, instrument time might be a means of separating applicants who have done significant IFR flying from those who have been primarily flying VFR like banner towing and carrying skydivers. For an airline far enough up on the food chain that applicants are from other airlines "instrument time" probably doesn't have much meaning. Once you have your ATP, and a couple of years of airline flying, "instrument time" and "night time" are probably pretty irrelevant.
That said, the regulation and Chief Counsel interpretation I quoted is *the* official stance of the FAA on the issue. The interpretation exists, precisely because the FAA has been asked the question, and the Interpretation is the FAA's official legal stance on what constitutes "instrument flight time".
I'm kind of at a loss for what basis you have for claiming that this is "out of date" or a red herring. Do you have anything at all to support your claim that the FAA has changed it's official legal stance on this issue? The current regulation is still worded the same, and as far as I know the FAA's Chief Counsel has not issued an interpretation which supersedes the one I quoted.
So what is your basis for claiming that this is no longer true?