I don't see why minimizing the number of validators is attractive. We want as many as possible precisely because that ensures that administrative control can't be seized. It's just like mining in Bitcoin -- you want it distributed into the hands of as many people as possible as evenly as possible. We are working on making this happen now. Obviously, open sourcing the server was a necessary stop to broadening the validators.
So the net result is that, since everyone - including the exchanges - trusts the OpenCoin-run nodes, the only safe thing to do is wait for OpenCoin's servers to come to a consensus amongst themselves and then accept their ledger updates in their entirety. There is no way for anyone outside of OpenCoin Inc to influence what gets included in the ledger except if you allow it.
It is true that today we control the majority of validators that other important servers trust. We're working now on increasing the number of validators because that will improve the reliability and robustness of the network. We absolutely do not want people to have to trust us, or even think they have to trust us, so this is a real priority for us. Open sourcing the server was, obviously, a step in this direction.
Last, if you're reading this, I'd suggest that you read up a bit about Ripple on Bitcoin Forum before you make conclusions about the currency - there are a lot of interesting discussions about its viability (like this one: https://bitcointalk.org/index.php?topic=146964.0).