Why don’t GIFs play in Photos (iOS or OSX)? They can be saved into Photos from other apps, and played by opening the GIF in Safari or by sending it to yourself in Messages. Even Quick Look in the Finder can play GIFs.
And why on Earth is Preview the default app for opening GIFs on OSX? Why does Preview separate the GIF into multiple pages, each with a single frame from the GIF? Trying to manipulate those pages (even quickly run down each image) will cause Preview to choke and stutter. It can even save an edit to a GIFs, but not play a GIF. It also can’t load a set of images and create a GIF from those. Does not compute.
Photos for iOS 9.3.3 (13G34); Photos (Mac OS X) 1.5 (370.42.0); Preview 8.1 (877.7).
Question for readers: How do I get the version number for an Apple iOS application?
Apple: Please Fix This 