There was a time when Walt Disney had almost completely shut down their 2D animation studio to concentrate only on 3D animation. This might sound a bit shocking for a company that is pretty high on the list of 2D animation studios, and in fact may be counted as the best by some. However, at that point of time, 2D animation was thought to be old technology which was not worth the time or effort that needed to be invested in it.
Today, it is a different story. 2D animation has found a newfound popularity and the list of 2D animation studios is growing. The development in 2D animation technology has made it easier and cheaper to make 2D animation, and it has found a market in a variety of fields other than films.
2D animation in its early years was a tedious and time consuming process. Since each frame of the film was hand drawn, and every minute of film had 1440 frames, it required a great number of animators to just render the frames. This made it very expensive to make 2D animation and was probably the most important reason why there were not many contenders on the list of 2D animation studios.
Today, with the Cel technology, 2D animation has become much easier and faster. Also, with the increased usage of computers for 2D animation, the list of 2D animation studios not only grows, but also finds more and more takers for this media, including website makers, corporate houses, and many other small businesses that cannot afford 3D animation.