Just wanted to chime in.
From the "google now" search, I can search for something, then tab over to images, and I'm shown a grid of images very similar to what I would see if I opened chrome and did a google image search. The thing is...it's different. When I do it this way, from the google now search, I do not get any options to download the image.
If I open chrome, go to google and do a search, from here, then go to images, I can long press and download images.
Basically there seems to be some kind of difference between a google now search and searching from google in chrome. Is this what the original poster was talking about, because it's annoying.