I used the media library when I started with WordPress but all the multiple size images generated tick me off. I wish WordPress would go the TimThumb route and resize dynamically, or at least generate the new files only when I need them. It's because of this that I chose to upload manually for a while, but went back to it when I saw the benefit of uploads having their own (attachment) pages.

Another thing that ticks me off: the "Title" field is required but not the "Alternate Text" field. You should always have an alt text for images in HTML. WordPress developers should know this and change this.

Lastly: Image URLs and locations should be dyamically generated, not hardcoded. WP should use shortcodes or something similar when I go into the HTML editor.