Good points, although I would never wish for de-evolution.
By measuring THC, CBD, and CBN content you are in no way guaranteeing the effect. The high comes not only from the cannabinoids (85 and counting) but terpenoids (125 and counting) play a role. They can modulate the effects of THC as well as reduce memory loss. They seem to play a role in sedation. Are Antioxidants. They play many more important roles, some yet understood. The food you ate, your hormone levels, many different factors also play a role in the 'high' you experience, and no one claims to know the high, by the cannabinoid ratio alone. Or, not honestly.
Generally, CBN ratio can be used to help bud-buyers measure how old the medicine is. As time passes, THC degraded to CBN, a less psychoactive cannabinoid. Not that you can tell exactly, but most places will shy away from any medicine with a higher CBN content.
By measuring cannabinoids you do multiple things. First, without it, we would never have found CBD rich strains. This has led to tons of research groups finding more and more about cannabidiol. A great thing. Education is always good. And yes, we are in our infancy of understanding the complete endocannabinoid recpetor system and how it interacts with our own endocannabinoids, as well as outside phytocannabinoids. And a LONG way off from being able to determine the high with numbers.
Terpene analysis is another interesting field. This will help get us a closer to a "grading" system where we can describe the high.
The goal is to save people time. A grower can market his medicine, and people can understand, without using terms like "fire". They can use objective facts, such as Cannabinoids analysis, pesticide screen, and mold screen to help show safe, quality medicine. This also helps add layers of legitimacy to a new industry, that is still looked at by many with skepticism, or worse.
And that's not even talking about edibles. Potency testing in edibles is crucial, in my opinion. How many times have you eaten too much? or not enough? Sometimes harder to self-dose with edibles.