If you think PNG is complex have a gander at webp. That plane crash is a single frame of vp8 video. Outside of a Rube Goldberg web browser the format is useless.
WebP is useful for lossless image storage for games/game engines, it takes roughly 80% of the time to load/decode vs the same image stored as a png, and is usually significantly (multiple megabytes) smaller for large textures. That stuff doesn't matter too much in a web browser, but in a game where you have potentially hundreds of these images being loaded and unloaded dynamically and every millisecond counts, it's worthwhile.
Erm, aren't both WebP and PNG rather useless for games? How do you convert those formats on the fly into one of the hardware-compressed texture formats consumed by the GPU (like BCx, ETC or ASTC)? If you're decoding PNG or WebP to one of the linear texture formats, you're wasting a ton of GPU memory and texture sampling bandwidth.
(these are probably better alternatives: https://github.com/BinomialLLC/basis_universal, or http://www.radgametools.com/oodletexture.htm)