For the sake of quoting Greg Maxwell, I'd like to pick a nit. Bitcoin has no rules other than those you enforce yourself, and all these pools did was enforce fewer rules of their fellow players, than we assume they do.[4]

Optimize would be less judgmental than cheat and speaks more precisely to the motivations[1]... we do need to be careful about this and make sure we're managing the incentives. Cheating is a moral judgement[2]

Bonus quote, unearthed while digging up the above:

While the identifiable parties in question here were Chinese; the first miners I saw doing this in the pastwere not Chinese-- it's not a Chinese specific issue; its a response to orphan rate. (China just has lots of hash power and poor connectivity).[3]

[1] https://www.reddit.com/r/Bitcoin/comments/3c305f/if_you_are_...

[2] https://www.reddit.com/r/BitcoinMarkets/comments/3c2jci/dail...

[3] https://www.reddit.com/r/Bitcoin/comments/3c305f/if_you_are_...

[4] One could interpret the block version increment as a policy advertisement, but you know what they say about assumptions.