[wp-hackers] Why are <img> tags inserted into posts?

[MikeD]

I'm wondering why an actual HTML <img> link is embedded into a post when inserting an image, as opposed to a shortcode such as

[img id=123 size='medium' alt='alt']

or something similar that would make site-wide changes to image sizes etc easier. Is it just the DB hit or was there some other reason? I'd love to read the history of this if it exists somewhere.