Me too, I think WP’s text editor is too smart, and plays god over code which dummies like myself would like to leave in a post.
Same problem here, at least that wysiwyg editor wipes out <p> tags and doesn’t allow what it believes to be invalid spaces between lines. Is it too smart? twinscards.com/blog
I tried adding this line of code at the top of my functions page, but after doing so it just runs all of the three lines together, without a break. The shift+enter thing does the same thing, and upon saving, treats the lines like paragraphs.
I see the validity of using CSS for some things, but for images it sure would be nice to be able to place the spaces as I need for each post.