Four years later and this is still a very much needed feature.
We collect rates list from our hundreds of suppliers every year, which for ease of use we save in a separate database organized by region, supplier, and year. When suppliers send us their rates in the email body, rather than in a separate PDF or Word document, our standard practice is to print the email to PDF and save it to the appropriate folder. Having the ability to print or save emails directly from the HubSpot inbox would save us valuable time and brain cells.