Yes, if you are trying to view pictures of flowers, then you are right. They should not add the pictures merely for decorations, but if you want to view a document explaining flowers then it is helpful to include the pictures of the flowers being described. (Similar thing is valid for other kind of documents that might have pictures of whatever is being described, but many documents should not need as many pictures as they too often have.)
Why are things “merely for decorations” bad? A ton of what we do in the world is for aesthetic reasons, why shouldn’t that include web content? Things looking nice is an important thing for many people.
Wastes space on the screen (especially if you have to scroll the screen to read it, or if you want to print it out and you want to save paper and ink), might sometimes make it more difficult to understand (in case you do not know what is the significance of the picture), and can use up power and disk space, etc.
However, sometimes it might help if you can specify which ones are merely for decoration and what is what, that you can easily disable them and to avoid downloading them. (Even if a picture is meant to be a significant part of the document because it is what it is about, then you still might not want to download it right away although it would help to display a placeholder (e.g. a hyperlink) in that case.)
