I've only been playing for a bit, but thought I might put a couple of ideas forward, around collaboration.
1) Maybe there could be large pots, with the item(s) to be collected at the bottom, but they need filling up with water(?) to get the items out. If they drained faster than one (or two) Glitches could fill it, then it would take a few people working together to get the items out?
2) Possibly could look at having the Rooks 'nest' in abandoned streets? They could move into the trees, and then start dropping feathers, that would make the streets impassable (eventually), if the feathers took a while to clear away, so that it took groups of Glitches working together to clear the feathers and nests, maybe that would make a reasonable group activity to work together on?
Just a couple of ideas, don't know if they're of much use, but thought I'd put them up here.