iTunes performs both of the those functions, albeit to a lesser degree of sophistication.
itunes can't rename my files, especially based off my tags
itunes will tag your mp3's, but you have to self edit them. my programs do the tags for me with a simple auto-tag click.
itunes will not save the download album art to the mp3. i have to use a Doug script to do this.
iTunes should be able to do more than it can. Way more. It should be the end all be all, but like the iPhone and MMS, Apple simply overlooked it, forgotten about it, or just doesn't give a damn. Too busy bloating iTunes with media for purchasing.