How do you minify and concatenate your files in your projects? Part of a deploy/build script? Commit hooks? Manually? Do you do it at all? What about compiling Sass and CoffeeScript?
The asset pipeline is not arrogance it's convenience. If you have a better system for those tasks then you shouldn't use the pipeline, but for a lot of people the asset pipeline saves time and results in a faster, better experience for their end users.