>There is no way you could push down the market 10 percent today.
GDAX fell about 8% yesterday, from $96.82 to $89.07 in one hour (May 4, 9-10am) with about $2 million worth of trades. It's a little early to call this a post-volatility era.
It's volatile alright, but that's not the same thing as being able to push the market down with a retail-sized trade, let alone push it down a staggering 10%. And just because the market dropped 8%, doesn't mean the drop can be attributed to $2 million worth of Ether put up for sale on GDAX.
The daily trading volume is $300 million at last count. There's arbitrage happening across exchanges so the price on one exchange is not isolated from what's happening on others.
There is no way you could push down the market 10 percent today. Maybe back in 2011, or maybe in one of the lesser known cryptocurrency markets. But in Ethereum, you could unload a huge number of ETH and the price wouldn't budge. I'm assuming of course you're not an institutional trader, in which case of course Ethereum trading volumes are insufficient to absorb large trades without significant price movements.
>Smart contracts are seriously entirely useless unless you solve oracles.
Even a basic cryptocurrency transaction (sending ETH from Account 1 to Account 2) utilizes smart contracts. Having Turing Complete script evaluation just means the range of smart contracts possible becomes larger. So for example, schemes like Lightning Network are possible with Ethereum, without any changes to the protocol.