Agreed... This appears to be a basic function. I'm also in the Engineering services business and it's critical for my line of work to show amount on the estimate, the amount billed to date, and the amount billed now on the PDF Invoice as well as the Emails. 

It's amazing to see these option appear in email format but does not appear on the PDF.  QBO by Intuit needs to adapt and innovate or it'll be eaten up by it's competitors.  QBO will force me to look into other options if things don't turn around quickly...