Another downside is all the polution that comes from the production... sure, you are purchasing something that gets you further ona gallon of gas, but how much gas did it take to produce? In the long run, and probably for the next decade, its just something that makes people feel good, while the standard wranger ends up being the ultimate financially* and enviromentally responcible choice.
The pollution levels are difficult to quantify and compare directly, particularly since they're different in nature (gas emissions vs. heavy metals, among other things). However, you're talking about pollution from a few sources vs. many sources. It's generally much easier to control pollution and emissions from a few large sources than it is from many smaller sources.
(*By finacially, I mean the ability to go int he long run and get passed down 2 or more owners is greater, where as in hybrids now and going forward, they have a high cost, incredible battery replacement costs, and possibly never have a new batter to replace with, as welll as software upgrades going forward. Just like it isnt much viable to buy a used PC, it isnt going to be much viable to buy a 10year old electric vehicle, especially for those with limited funds)
The computer to car comparison isn't a very good one... computers became obsolete very quickly in the past, and computers generally require fairly recent software to be of use. A car has a simple purpose - to move. Whether it becomes outdated in terms of software doesn't really mean much aside from possibly taking a hit to resale value; the car is still going to move.
It remains to be seen how the longevity of hybrids and electric vehicles will be.