Thanks for the informative post NLCRich. I think I finally get why I couldn't enjoy that much the Smithing perk tree in the game.
It only focus on player character and has no impact on player's party at all.
So, in vanilla, with new Smithing perks or not, player only get improvement for PC(Player Character) itself, which makes both of its branches meaningless if the player don't care much about fancy customized weapons, since it only makes a character, either PC or the companion, a helper at the forge or a main crafter.
I think it would be better if this perk tree could do more than this. Let's say, one of the branches focus on creating master piece like the vanilla, while the other branch focus on improvements that could affect the player's army.
The master piece creating branch could be still similar to the vanilla one, but merging two vanilla branches into one, while the second branch, the new branch could give a discount when upgrading units from tier1 to tier2, tier2 to tier3, tier3 to tier4 if you were upgrading your units in a settlement with a smithing workshop owned by you. Or, making your owned smithing workshop more profitable, or even unlock a policy for your realm that allows you to make upgrading elite tier units much cheaper.
The names for the new perks, if implantable, could be something like, Abrove the Farm Tools(cheaper T1~T2), Basic Protection(Cheaper T2~T3), Standardlized Production(Cheaper T3~T4), Apprenticeship(No longer spent stamina in workshop, but also significantly reduce the quality of the crafted item by characters with this perk), Massive production(enable the production of charcoal and ingot from hardwood and ore for trading), Guild of Forges(make ingot and charcoal more profitable), Armor Dealer(more profitable with Tanner Workshop), Decorated Art Piece(more profitable with Jewellery Wrokshop), Forges for War(your army and the faction you own has cheaper elite tier unit upgrade).
And if the policy could be related and unlocked by a perk, then we should be able to play around with this trick a little more with other perk trees. Like the trading, a perk in trading unlocks a policy to order certain goods such as horses from a notable merchant from a non-hostile settlement. Or in Steward, unlocks a policy to obligate the owned villages to provide food or horses from time to time.
I think if the game could make it hard to get a large elite army(more expensive), then the non-combat-related skills would became more favorable to the players in the SP campaign. Because that's when we have to choose, to either have an elite but small party or large but average strength party; to either enlist cultural units or rely on mostly mercenaries to keep you safe; to either develop and prosper your realm to maintain your troops or to raid and pillage to keep things together.