You don't have to convince me. Writing HTML e-mails, especially for higher ups that have no concern for the limitations of the platform, is awful. This is why I just insist on using Mailchimp templates these days[1]. They've done the hard work, it just works (usually), let's just focus on content.
[1]Pick your poison, but I find Mailchimp a great mix of easy to use, flexible, and functional.