BitAssets (bitUSD, bitCNY, ... bitGold) are designed to track the price of those "real world" assets without counterparty risk on the blockchain.

So think of them as financial tools.  You can switch your exposure to price movements in 3 seconds by trading between them.

Think of BitShares as a special purpose currency factory that offers a way to create a variety of useful hybrid "smart coins" that breed desirable features from multiple currency strains.  Some are trustless.  Some engineer blockchain-assisted trust.  Some represent real assets mapped onto the blockchain by trust alone. Others are stable with respect to external assets that may or may not be stable themselves.  Some are deterministically self-contained mathematical constructs.  Others extract order from the unpredictable external consensus of generally clueless people.  Our industry is generating a Cambrian Explosion of new coin species. 

So, when you evaluate any particular coin, you shouldn't be comparing it to some preconceived idea of what your ideal one-size-fits-all universal coin should be.  That's like saying everyone should standardize on a single retirement mutual fund.   The blockchain world has moved waaaaaay beyond that.