I had assumed Google Photos was the Picassa code rebranded. Since Picassa was the engine for photos in G+, and then G+ photos moved to Google Photos, it never

I had assumed Google Photos was the Picassa code rebranded. Since Picassa was the engine for photos in G+, and then G+ photos moved to Google Photos, it never dawned on me that Picassa was still running as its own separate thing. I wonder why they felt compelled to redo photos?