To paraphrase someone else's post in the forum, one of the intrinsic characteristics of Bitcoin is that every node needs to hear about every transaction. For example, every purchase of a child's popsicle or every microbet on a digital lottery. That's just the way the system works. Another characteristic is that individual nodes do not need to have trust in any other nodes for the system to work.

Ripple solves different problems than Bitcoin, and it seems to me that in exchange for getting decentralized scalability to infinity and multiple currencies, the price is that you have to trust at least one node (among other things). It seems reasonable to also accept that another unique property of Ripple is that, unlike Bitcoin, it must be bootstrapped in a centralized way. There needs to be that initial node of trust (unlike Bitcoin).

It is probably too early to worry about Ripple's current lack of decentralization. Bigger problems are:

1) Confusion over the role of XRPs
2) Lack of mathematical proofs of the security and performance of the system
3) Missing source code

We can't even determine if Ripple can be decentralized until we have answers to the three points above.