I’d like to reply on what you said there Ross; having an option to disable the entire CSS file from being loaded would be truly helpful! That way it’s up to the developer/designer to style the whole thing. Which, in my opinion, would be best.
Having the ability to enqueue the stylesheet and script files on ID-base (or whatever other method) would allow people to only load it on the pages they want. I guess this offers the most functionality. Plus it keeps PageSpeed in mind and all that. This way they can load it only when necessary. And I can stop the CSS from loading completely.
Maybe something like this for the config or functions file?
define('WPCF7_LOAD_JS', false);
define('WPCF7_LOAD_CSS', false);
(Example taken from the contact 7 form plug-in way to enqueue.)