You are talking about the situation as it is today. 101 nodes might be acceptable to some for the amount of users in the network today.
To the contrary, RIGHT NOW all other systems are more decentralized because they are small enough to afford more than 100 validators. DPOS will only become more decentralized AT SCALE, when you cannot afford that many validators unless you force them to be distinct. The argument is presented in depth in a few places:
http://bytemaster.bitshares.org/article/2015/01/07/The-Most-Decentralized-Proof-of-Stake-System/http://wiki.bitshares.org/index.php/DPOS#ScalabilityBut as I said in my previous post, focusing on the ratio of block validators to users is a red herring. Focus on the ratio of stake in the network to influence over network behavior. Other POS systems force out the little guy.