If someone wants to sue Google for stealing images, i would support.
And, that doesn't apply for few webmasters only, but all the webmasters who have their websites online. So, in short, Google is now stealing images. If they tell that people should block their bot, they should tell that everyone should block their bot.
Its purely stealing. Our client is using high resolution images from Getty Images and other agencies. Google is stealing those images. I am sure, Getty Images or other agencies also won't like this.