too many image sizes in a responsive theme

one of the disvantages of a resposive theme is that it has to create too many image sizes to serve different screens.

For example, if we support 4 screens (mobile portrait, table portrait, HD - 1280px, Full HD - 1920px) and we have 2 different image sizes in one screen. It will need 4 * 2 = 8 sizes. And, to serve retina screens, it needs 8 * 2 = 16 sizes.

Well, that’s the minimum number. For a more flexible theme, that number would increase multiple-times

How do you guys deal with it? How to answer customers who do not want their server to be flooded with image thumbnails?