In addition to getting flack for saying that saving in RAW is usually a waste of time, I also got flack for saying that electronic viewfinders are overrated in my Samsung NX200 review. Someone even said that they wanted to punch me in the face!
It's true, though--viewfinders are not essential. As long as you have something to look at or through that allows you to compose your image, that's all you really need. Anything above that is a luxury.
If you have a viewfinder, great! If you don't, so what? Is it better to place your eye right up to a tiny screen or 12 inches from a larger one? The obvious answer is that it doesn't matter.
Some people believe that looking through a small window near the top of the camera is the best way to compose an image, and that any other way is inferior. As I see it, as long as you are able to compose the image, that is what is important, and the means to accomplish that is irrelevant.
I think sometimes people forget that photography is not nor has ever been about the equipment (shhh, don't tell Leica owners I said that...). Photography is about the photograph. More importantly, it's what the photograph communicates to the one viewing it. The means of creating that photograph matter not to the viewer, only the final image that is in front of him or her and the message that it carries to that person.
I think there is a lesson that some photographers never learned because they have never used primitive equipment from photography's past (or a Holga, which is a primitive camera from modern China). That equipment can be used to craft photographs that would blow away what modern equipment can capture.
All one needs to craft a great photograph is something sensitive to light and a hole. A year long exposure of Toronto's skyline made from a pinhole and some reversal paper is more intriguing than 99.9% of photographs made with modern DSLRs. No viewfinder was used or needed.
Today's modern cameras are like luxury cars: plush, handles well, full of features. But all of that doesn't translate to a thrilling driving experience or a great photograph. The intent is to make your comfortable. A great thrill or great art rarely happens when one is comfortable.
So is it important if a camera has an electronic viewfinder? No, it is not.
What people should be more worried about is if they are capable of taking great photographs. People get too caught up in the equipment they own or want to own (or don't want to own) and completely miss what is truly important.
Either you can craft great photographs with any camera or you can't craft great photographs no matter the camera. Just because a camera has some feature doesn't mean whatsoever that it will take better photographs and just because a camera lacks some feature doesn't mean whatsoever that it will take worse photographs.
Photographs, which are what photography is all about, are made by photographers and not by cameras. The skill of the photographer is far more important to the outcome of an image than the camera is.
Ansel Adams said, "The single most important component of a camera is the twelve inches behind it."
In other words, if the twelve inches behind the camera are not capable, than the camera is not, either. And if the twelve inches behind the camera are capable, than so is the camera, no matter the camera.
Again, if a camera has or doesn't have a viewfinder, it makes no difference. Either you can take great photographs with it or you can't, depending on if you are a skilled photographer or not.
Learn how to craft great photographs first, worry about what features your camera does or doesn't have some other day.