Might still be useful for alt SHA-256 coins but it's too late for BTC now
All alt sha256 are lower value than BTC, so , useless ...
The thinking is more would be accumulated, and there would be greater leverage on gains when picking the correct alt coin to trade against BTC. The trick is picking the correct alt coin, and the odds are stacked against someone doing that hence part of the risk/reward model that rewards largely, but less often, to those who take the most risk. Adding another layer of risk, speculating on emerging coins, is usually too much for most of us to stomach; I certainly don't want to bother, for me BTC is the risky one, and all the other coins I might as well play Satoshi Dice. But that might shift in two months depending on the price of BTC or my power costs... If this were a craps table and BTC were a pass line bet, all the alt coins are like the "hard way" bets, they have the potential to pay out higher, but the odds are against you on picking the right one. And value is relative, the idea is to trade against BTC or cash or whatever with the other coin, then through trade to obtain more than you could by mining directly. It's the same reason nations have imports and exports, they leverage the resources available to trade for greater amounts of things they lack resources to create and thus meet demand and achieve optimal profits.