"The true problem is that when crafting an email 95% of the time is spent getting the design just right and only 5% is spent on the subject and content."

I'm curious what shop you are thinking of that has this kind of time breakdown? I know that in my previous agency (political/non-profit/corporate consulting), the team responsible for emails spent hours and hours working on crafting perfect subject lines and meaningful content. The subject and the content drove the design.