Idea of StableCoin have no real meaning.
StableCoin it should be stable regarding what?
Stable against the dollar? It means that it will be not crypto coin – it will be USD wallet.
Stable against the gold or oil? It means that it will be gold futures, not crypto coin.
Stable – it’s economic property of the coin and not a technological feature. Bitcoin can be stable like gold with sufficient prevalence.
You're completely right. I'm not a big fan of stablecoins either because it either relies on trust of a centralized entity, like Tether, while still having to trust that the fiat you're holding won't lose value dramatically, or the trust of a certain decentralized process, like BitUSD.
But it does play a role in some scenarios.
For example, in countries such as India where the government and the central bank has cracked down on bitcoin transactions, they have relied on stablecoins as a proxy in order to trade fiat against crypto. Of course, I would never consider stablecoins as a legitimate decentralized long term storage of wealth, nor am I concerned about bitcoin's fluctuations at the moment. I completely agree with the statement that with enough adoption, bitcoin will see intrinsic stability.