It actually would still create problems. The sets are only 39 cards big and have a greater number of higher rarity cards. As Dewize stated, you would be able to acquire spirit at a far higher rate even without taking into account disenchanting.
If this model were to continue, players would never have a reason to save up for or spend money on new packs. The amount of spirit they would be able to earn for such little effort would allow them to craft any card they wanted to use without needing to expose themselves to random chance, which I should point out is a major source of incentive for revenue generation.
As mentioned by Ryvirath, this would fall under the latter issue of requiring a rework to the distribution model. No matter which potential solution they could select to change this, it would require an immense amount of work to change.
I’m sorry you dislike certain cards in the game. I’m sorry you consider some cards poor enough to never use. All of us can sympathise with this to some degree. I’m not sorry, however, that you want it to change for your convenience. It’s just the way things go. 
