Higher level items could then increase complexity, forcing the crafter to acquire rarer/harder to acquire components. Developing this progression based system may be able to satisfy multiple parties.
Exactly. Low level, generic items should not be complicated to make. The more specialized the item, the more complex the requirements.

I predict this decision is due to the developers being unable to fully integrate the usefulness of crafting and gathering players into the main overwhelming threat to Eorzia storyline that they're currently writing. (end game/expansions/etc.)
And lets face it, to a degree, allowing DoH and DoL jobs to participate in the main storylines is probably why they are so lacking in interactive content. Yes there is Parley, but that's a bit lacking in satisfaction. It was a great idea, just not one in which was workable in the manner they provided. Now, if they made those jobs truly combat capable (as they should have done to an extent), it could have. Imaging if Weavers could wield various types of shears and needles, or butcher knives and skillets for Cooks. Miners use pickaxes and sledgehammers, why aren't they able to attack with those?