Although it would be easy for you, it wouldn't work as well for other people. I am not so knowledgeable about music formats so I will use image formats as an example. The same sort of thing applies for music formats.

If we just used .bmp for image formats, we would fill up our hard drives because of the huge sizes, and web pages would take ages to load. If we only used .jpg every time we saved an image, the image would lose quality. We also wouldn't have transparencies. A lot of computer games use .tga files, but others use .dds because it has mipmaps.

It is the same sort of thing for music, each format has its advantages and drawbacks.

Different formats are good for different things like people have said above me. To scrap all formats and make one basic one would ruin the reason for having formats. If all image formats were grouped into one we would loose the specialty of some to compress really big images and some to compress small images.

I have had this frustration when uploading videos though. Most people have a flash plugin for their browser, but some people do not, so saving as a swf is not always safe. All pcs should run wmv fine but what about macs and linux? .mov for quicktime is a nice format, but lots of people on pcs will not be able to watch it without installing quicktime.

So no format is perfect, but by making a sacrific here and there you can find some pros or having different formats. In my situation there are no pros to different formats, persay, but you see what I'm getting at.