Surplus was a horrible idea. It should be obvious to most that artificially impeding your players is annoying to most, and people generally don't play games to be annoyed. It's so easy to hit surplus even if you play casually, and the hardcores it was meant to impede simply powered through it at a reduced pace, but still miles ahead of the people this was meant to serve.
While the intention to aid casuals is all well and good, the implementation was done poorly. Punishing those who played a more than a couple hours a day, and instead of helping those that didn't.
People harp about it being encouraging you to play other classes, but if people aren't interested in playing those others, do you know what they do? They stop playing, as countless people have. Surplus is one of many mechanics that this game got repeatedly trashed for when it was released, and especially now, it serves no positive purpose.