Great that some more tables on the frontpage are gone The new function "print_simple_box_start" looks like a great solution for backward compatibility.
I suppose colour and width are taken over from pre CSS times.But the inline styles that are used are reducing flexibility. The inline style has the highest possible specificity and is hard to overwrite. You can overwrite it only with "!important" - and that's really bad because you loose much flexibility. All html attributes you can overwrite with CSS but not inline styles.
Did you consider other solutions? The only solution I know is to take colour and width out of the box definition. These values should really go into the CSS files.
Please let's take them out if there aren't better solutions.