I wouldn't say that optical viewfinders are much better, I would put it such that both have their selling points and diminishing points.
Firstly, EVF does give you eye strain after prolonged usage, cos you're using one eye to stare at such a small monitor at a close range, and frequently squinting to see the details. And secondly, EVF is useless at night (for most DCs). It will be almost pitch dark, only showing the bright lights like street lamps, so composition of the picture is one big problem. However some cams like the Dimage 5/7 actually compensate for that by brightening up the display.
Then comes the good points of EVF. It lets you see lots of things that the optical viewfinder doesn't. Exposure information like shutter speed and aperture, ISO can be seen at one glance. In MF, focussing distance is shown as well. Exposure compensation is nicely tucked away in one corner of the screen too. This may clutter up the screen, but I like it with all the info there when I need them. Also, exposure can be checked immediately, as the EVF usually shows you what the final image will more or less look like. You make EV compensation, then image is refreshed to show you the effect. You can also check focus, when you half-press the shutter, to see if the cam focussed on your intended subject.
All the above are not possible with an optical viewfinder (of consumer-level DCs), but note that they can be accomplished with the LCD of the camera anyway. It's just that EVF is a energy-conserving type of LCD, and if you like to frame your shots using the viewfinder instead of the LCD screen, the EVF is quite a gem.
And also, the parallex error associated with the OVF will magnify when taking macro or close-up shots, so it's better to use the LCD. EVF wouldn't have the same problem.
Ok so this is my breakdown, both types of viewfinders have their pros and cons. In my opinion, the best viewfinder is still that of SLRs.