I guess as flecc pointed out too, the battery technology just isn't good advanced enough yet or cheap enough. Manufacturers are nervous about warranty side of things I expect.
So much so that the Leaf's rivals based on the Mitsubishi electric i-car and also from Peugeot/Citroen are only leasing them for a four year term, clearly the battery life since they won't contemplate longer. The ownership and use costs are similar to the Leaf, just a little less.
I don't buy the suppression of new technology argument. Manufacturers don't care what makes their money and e-cars could be a whole new market in part adding to their current business. The simple fact is that current factors make e-cars a dead end.
1) The batteries are technically well short of what is needed, a claimed 90 mile range which in truth is 60/70 miles with normal driving just isn't enough, especially when the battery's range declines as it ages. It could be only 40 miles as it nears four years old.
2) The low demand and consequent small and expensive production makes fundamental prices too high.
3) The failures of untried technology, especially the large batteries, means warranty costs could be high, adding to the initial pricing.
4) Lithium is a scarce resource and there isn't a cat-in-hells chance of there being enough for even a small proportion of us owning e-cars.
5) There's no agreement on the battery technology to use, each being the least bad of a poor bunch. Smart and the Think car use "salt" technology which is only any use in constantly used cars. Others use LiFePO
4 and variants like sulphur. There's also the rival part time petrol full hybrids like the Chevrolet Volt and Chinese BYD, though the latter seems to be hitting production and sales problems with hints of technical troubles too.
I see current e-cars as mainly there to please the politicians by satisfying their demands. If/when they fail in the market the politicians can't say the industry hasn't tried.