50mm Prime?
I'm among the people who recommend a lens of the type this article discusses.
Firstly, there's no arguing that the times and lens technology have changed, and that many people buying a kit can be well-served by a kit zoom.
I don't actually recommend a "50mm prime" per se, but a "fast prime". By "fast" I mean hopefully faster than f/2.8 (the smaller the number, the faster. The main reason for this recommendation is to better enable subject isolation through depth-of-field manipulation. Many beginners don't understand how the speed of the lens can radically improve the look of one's photographs, but they'll see it quickly if they own a lens like this. Modern digital cameras are wonderful for enabling a simple experiment to instantly see what a large aperture can do for the look of a photo.
Why a prime lens then? ("Prime" means fixed focal length, or not-a-zoom.) There are a few arguments. Many make the argument that it makes the photographer think about positioning and composition more if they have to physically move to frame a picture. My main reasons for recommending a prime are more practical: cost and relative quality.
Fast, high quality zoom lenses are really expensive, while a "normal" field-of-view prime lens is usually pretty reasonably priced and easy to make, so the quality of the lens is typically very high. Even with the advances in lens tech, it's hard to build a very good lens with the ability to isolate subjects.
An f/4-4.5 (or even 5.6) kit zoom just isn't going to give that kind of quality or isolation, and a new consumer isn't going to know what they're missing. In my mind, someone in that position is going to get a lot of power in their DSLR, and still not make as striking a picture as someone with a less-capable camera with a fast prime.
So, what about the 50mm part? The author explains it a bit: you probably will be well-served if your first fast prime has a pretty "normal" field-of-view, whereby "normal", we usually mean something that approximates the field-of-view of an average human's vision. For 35mm cameras (and "full frame" cameras like Nikon FX, that is around a 50mm. For crop-sensor cameras like the consumer-level Canon EOS and Nikon DX cameras, it's in the 30mm range or so. For Micro Four-Thirds, it's a 25mm-ish lens. I tend to like something ever-so-slightly wider, like a 35-40mm effective focal length, but I do really like my 50mm f/1.4 G Nikkor.
I'm sticking to my guns: Buy a fast prime and I bet your images improve in quality and you'll appreciate what makes your DSLR or EVIL camera a lot more. You won't need it if you're just going to shoot your kid's soccer games from the sidelines, but you'll love how portraits look, and you'll love how much better pictures taken in low light are, regardless of the subject. If you can't buy anything more than a kit zoom, I'd even recommend a nice compact camera instead.
(If you are just shooting your kid's soccer game, do yourself a favor and check out the Nikon 1. It's as fast in every important way as a DSLR for that task, and you can get some really impressive reach for relatively cheap with that system.)
Photographic Myths and Platitudes: New DSLR? Why You Do NOT Need a 50mm Prime
(Note: This article has been slightly revised and updated since it was originally posted in 2012.) From time to time I share here my response to a question that I fielded somewhere else. In this ca...