I guess hiding the ads doesn’t save bandwidth & removing the ads saves the bandwidth.
If I visit kickass torrent site with AdblockPlus then ads are not there & no white space.
If I visit kickass torrent site with adSanitizer then ads are not there but in the place of ads the whole white space is there.
Those ads in Search are there because Google makes money from them. They are part of your search results, and therefore cannot be removed by ad blockers/etc.