The crafted spells are most useful for lower level wizards (around level 20-30). At higher levels, they are not really useful for play. However, because you have to be questing in Zafaria before you can work on legendary artisan, lower level wizards can only get these spells from packs.
Crafting these spells would be fun and challenging, and I'd love to be able to play them in the game. But as it stands, it isn't worth it.
If KI wanted to restrict these spells by level, the way ordinary spells are restricted, that would be one thing. But allowing them for any level from packs but not till Zafaria for crafting is unbalanced.
Please consider making these spells available at lower levels.