I think there is a pattern with Google:
Social network: Orkut was their one and only working social network. Google - it is not great, so we raze it to the ground and make a better product... and they were trying to do so for last 12 years.
Messenger: Talk was their one and only working messenger. Google - it is not great, so we raze it to the ground and make a better product... and they were trying to do so for last 12 years.
Photo blog: Picasa was their one and only working photo blog. Google - it is not great, so we raze it to the ground and make a better product... and they were trying to do so for last 12 years.
New site: Reader was their one and only working news portal. Google - it is not great, so we raze it to the ground and make a better product... and they were trying to do so for last 12 years.
Casual blog: Blogger was their one and only working casual blogging site. Google - it is not great, so we raze it to the ground and make a better product... and they were trying to do so for last 12 years.
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Google Photos is such a faceless product to the extend you get surprised time after time again to the fact of its existence when you see it popping up under different names after firmware updates.
Picasa was a photoblog, something with essence, community, and vaguely stated purpose. Photos, on the other hand... well, just a file dumpster with UI.