In bitcoin, the anonymity is ensured by creating a new address for each transaction and by associating this address with a wallet. As far as I understand, with NXT, you use your account (calculated by the system from your passphrase) for every transaction, so it is simple by browsing the blockchain to trace all exchanges behind an account and a person. Is there any plan to address that ?
It's not hard to use Bitcoin approach in client software. NRS (Nxt Reference Software) doesn't support this because anonymity is not ensured this way, it only creates a delusion of anonymity (http://people.csail.mit.edu/spillai/data/papers/bitcoin-transaction-graph-analysis.pdf). CoinShuffle (http://crypsys.mmci.uni-saarland.de/projects/CoinShuffle/coinshuffle.pdf) will be added to Nxt soon to provide a better protection against deanonymization.