That's quite a sugar coating.
The portion of the decline that I experienced since feb 08 was due to bugs that prevented people from being able to play and an erosion in rp.
I recal an outage that lasted for weeks back in 08 that erased a good chung of the population.
After that the game stabalized for a while however many good players had left.
Over time there were fewer and fewer role players in game.
We as players did what we could to stimulate rp. The outlaws ran many rp events trying to invite players as we played.
The 0.5 update came out along with its bugs and new system requirements. This erased a significant portion of the player population.
With many good players missing rp was very difficult if not impossible.
More players left as a result of the loss of players.
For the sake of ps, hopefully the players who stayed and the new ones who joined since will figure things out and prosper

There were many arguments over in game issues but I think the above is what caused most of the decline.