3D Animated films are created with various programs. I'll list ones i know of, Maya, Houdini, 3Ds max....i think Maya and 3Ds Max are the main ones.

2D Animated films are created with ToonBoom, Flash, (usually Adobe After effects is used in some cases.)

Of coarse they're many more programs. It takes a long time especially for 2D because you need to create 24-30 drawings per second of film. (Time varies but the standard is 24fps-frames per second.) On top of that it goes to a key Animator to draw up the basic poses and timing and then to a junior Animation for the in-betweens that connect each pose together. Then you have storyboard artists, character design, colour, special effects blah blah blah. So it takes a bit of time. (The Princess and the Frog was created using Toonboom, and i believe that the Simpsons use this program as well.)

3D is a bit simpler because you can manipulate a rigged character to a pose, work out the timing to the next pose and the program puts everything in-between. (Flash can do this too, but Flash is usually used for television vs theatre releases. Its easy to spot a flash Cartoon they are usually stiff and not really that well animated. ( I heard Southpark uses Maya oddly)

Movies cost a lot when you add up all the departments it takes to make a movie. For 3D you need a modeller to model the objects, characters, backgrounds for the movie. You need a texture artist that applies a rendered surface so that lets say a ball would be modelled and by default its grey (in Maya) and then the texture artist comes in and applies colour and whatever with texture maps. Then you need a Character Rigger that will rig a character so that when you manipulate a characters body part it'll act natural like a real body would. Then you need a weight painter that pretty much paints onto the character model telling Maya when the left hand moves, this area of the model moves with it ....its hard to explain the weights painted process. Then you have Character Animators that Animated the characters, special effects artists (who do stuff like rain, how a bottle would break when struck, lazer beams, dust, whatever else...these are just examples.) Then you have a Lighting department that takes care of manipulating real life type of lighting inside each scene of an animation. Production staff that do the things like mentioned above, character design, background design, storyboards, rigging, modelling and so on. Sound department and a rendering department. Rendering is interesting because what it'll do is take all this information (Animation, textures, models, lighting, sound, whatever else) and combine it together for the end product. Rendering can take months to finish for a feather film. It eats up a lot of time in the production of a film. I know you can search to find out how long it takes to render each scene. For example a simple household computer like mine took 2 weeks to render out a small uncomplicated 1min short. Theres more info on this subject, if you wish to know more about Animation it self heres a couple books i can think of;

The Illustration of Life- Disney
The Animators Survival guide <-MUST HAVE

Anyways, you add this together and you're paying you staff quite a bit for a year or two or more's work for theatre length film. Television is a bit cheaper and everything seems to be going the flash route which is a lot quicker to do a 20min episode which is less money the studio eats up financially.