There is more to decentralization than just the nodes. It also is in the accumulation of currency. Since the creator kept the bulk of the currency they have total ability to manipulate the market by what they do with that currency. So it is centralized there as well.
There are other cryptos out there that do similar things, but are not setup like ripple.
I was invested in it quite a bit for a couple of weeks and recommended it to other people. It's not for me now though.