Agreed on what happened with the other chains but I don't think the abusers left. They just didn't have to work to sneak in their abuse anymore since they were able to just get tokens without seeking consensus. Those kinds of users then don't have to work for the token and are much more inclined to sell off the tokens versus using it to increase their influence on rewards. This leads to a price decline for the token value since users have no reason to buy to increase their influence and the sellers just push price lower.
I seen someone else leave a comment that explains it well. If witnesses really support that concept then they should have no issue with removing witness rewards from the chain. If they need to be rewarded for their efforts then we'll just issue a second layer token and reward them with it. If they expect non-chain level tokens to be good enough for users then it should be good enough for them as well I would assume.