Why do they need it? Because not everyone can afford, nor may wish, to buy widgets (keys in this instance).
Also, not everyone got the same luck with the orbs as you did, in fact many complained here about how hard it was to progress along.
Furthermore, the average player is not able to maximize collection of city litter.
The quests are scaled to represent buildings that are "at the current or previous chapter's level", so that means that the houses, workshops, barracks, armories, and factories all need to be in this general vicinity, and not everyone is able to keep this up.
My scouts take around 50 hours to report back, and I play a balanced game, so for many high level players it's somewhere between 48 and 80 hours.
If you are endgame, there is no research.
Upgrade a building, at least we are able to use RR spells (if we have them, not everyone does).
So then we are looking at having the ability to craft, and craft again, a whole lot of quests. Some can do this, some cannot. I have cities that do not, even yet, have a single Moonstone Library.