The Google Web Search Help forum is filled with complaints from Google users that no longer see their custom background images they used on their Google home page for the past two plus years.
From Frogs to Models, they are all gone:
The complaints are so massive and widespread that Google added to the home page of the forum a link to where people should submit their complaints. It isn't stopping people from creating their own threads, which Googlers are merging into the main thread.
Here is a picture of the forum instructions:
The main thread itself has well over three hundred posts but trust me, there is a lot more going on in the Google Web Search Help forums on this topic.
Google did announced the last Friday in September that this feature is going away. There is even a help page about the change.
I am sure there are plenty browser extensions you can use to continue to customize your Google home page but it is no longer backed into Google.
Forum discussion at Google Web Search Help.