"What I would like to see is the developers taking an approach similar to what I did"
What makes you think they didn't? I would be astounded if they didn't have predictive models that they rely on for initial card designs.
Demon hunter does. Take Glaivebound Adept for example, this has an efficiency of 130%. That is quite high when compared to other cards. Priestess of Fury only has an efficiency of 142%, which is reflected by it being a ridiculously good seven drop. However, they decided to print Raging Felscreamer which can make this card a 5 drop. This makes the card have an efficiency of 190% when played on curve with cost reduction. This is an insane amount of value, reflected by the efficiency.
There are other strong cards that each class will have huge value with, Reno for example, but they are most often situational, later game and legendary. The combo I mentioned is very easy to pull off especially with all the card draw DH has. This leads me to think blizzard either doesn’t have these metrics or doesn’t care about them.