We (Sendicate) agree with your points. We have templates that automatically resize images, use readable fonts and colors, emphasize text and readability on mobile (even with multiple columns and dynamic layouts). We also automatically create a plain-text version without re-writing links for tracking. We have learnt from the mistakes of others and tried to solve the problems you describe. Email can be horrible, but it doesn't have to be.

The good news is that you can decide how to view your emails. For Apple Mail try running "defaults write com.apple.mail PreferPlainText -bool true"