If you look at Monero pools you'll see lots of miners with hashrates equivalent to 20,000 CPU cores and more and it wouldn't be profitable for people to buy or rent that many CPU cores.  So they're very likely using stolen processor cycles from infected computers that are controlled within a botnet.  Some large botnets can control the resources of up to a million infected computers without the legal owners of those computers even knowing.  These botnets get to use the spare CPU cycles and memory of the infected computers.  So adopting the cryptonight hashing algo would mean handing over the overwhelming majority of all newly hashed coins to a few small groups of criminals.  Going with a GPU biased hashing algo would give dedicated miners an advantage over the criminal owners of botnets.  Although if Anoncoin or the coins it merge-mines with within a myriad become very valuable.  Then botnets will still target GPU biased coins just that GPU miners will have an upper hand.  As even Bitcoin was still plagued by botnets in its GPU days at times.  The only way to truly avoid the botnet problem is to use ASIC's.  The only thing is though is that GPU's are more readily available to anyone who wishes to contribute to the network.  A lot of people and especially the cryptocoin types will already have GPU's that they can use to hash with.  While someone new to the game would find it a lot easier to buy or build a PC with a GPU fitted.  
PoW is supposed to be about fairly sharing the hashed coins to miners who help secure the network.  While the more individual miners a chain has then the more people who have a stake in that coins future.  So therefore more fanboys to help evangelise the benefits of the coins.  I'd suppose going ASIC would be fairer than going CPU only well at least it's stop criminals controlling the majority of the supply of all new coins.