Our scheme was never going to be perfect, and we have said on a few occasions that we will only be utilising a basic nizkp until zk-snarks is fully out and trustless.

The reason we opted for anonymous tokens, instead of direct anonymous outputs to ringsigs, is because we're building towards direction we're heading in. What we're striving for... Encrypted values, with perfect nizkps, proving all values of inputs are real, without revealing any information about where they come from.

We're looking at many things, like homomorphic encryption, snarks, etc...
http://eprint.iacr.org/2014/976
snarks are advancing, along with many other ideas... We are not for limiting ourselves, but for bettering our [collective] future