The tribe has, like every other tribe, had a long history of getting screwed over by greedy white men. In their particular case, this meant pretty much everyone from the New Zealand Company (1839 version) through to the confiscation and non-return of land during wartime that would become Noel Robinson's Pram airport (and licence to print money).
The signing comes after the landmark Tuhoe settlement, a crowning achievement in itself by Treaty Settlements Minister Chris Finlayson. What a difference a competent minister makes, as David Farrar's OIA on Treaty settlements shows.
To a point, anyway. Yes, Margaret Wilson was mediocre, Mark Burton was useless. Cullen picked up the slack a lot, but too late. However, process goes a long way too. Way back at the Treaty Lectures in 2006, Geoff Palmer and Judge Joe Williams pointed out half the hassle comes with the protocols of dealing with each iwi and hapu. In typical Kiwi vernacular, these obstacles were overcome first by "Template", followed by its newer version, "Amended Template". I wrote it up here, before revisiting the subject a year later here.
I tell ya, if you want to get a grip on Rauparaha, have a read of Edward Jerningham Wakefield's Adventure in New Zealand. It also helpfully lists what Wellington was sold for (pg 34):
The goods paid for the Wellington lands were -
100 red blankets 120 muskets 2 tierces of tobacco
48 iron pots 2 cases soap 15 fowling pieces
21 kegs gunpowder 1 case ball cartridges 1 keg lead slabs
100 cartouche boxes 100 tomahawks 40 pipe tomahawks
1 case pipes 2 dozen spades 10 dozen pairs scissors
1 dozen pairs shoes 1 dozen umbrellas 1 dozen hats
1 dozen razors 6 dozen hoes 1 dozen shaving boxes and brushes
1 dozen sticks sealing wax 50 steel axes 1,200 fish hooks
12 bullet moulds 12 dozen shirts 20 jackets
20 pairs trousers 60 red nightcaps 300 yards cotton duck
200 yards calico 100 yards check 2 dozen handkerchiefs
2 dozen slates 200 pencils 10 dozen looking glasses
10 dozen pocket knives 2 pounds beads 100 yards ribbon
1 gross Jews harps 10 dozen dressing combs
2 suits superfine clothes 1 dozen adzes
By the values of those days, these goods represented about 400 pounds.