It's actually very difficult to use these, for two reasons:
1. All the formats are lossy. So if you have something like nice clean pixel art, the lossy compression will probably add visible artefacts. They're designed for 3D games where things tend to be far away and so the detail less visible, but 2D games tend to require lossless textures.
2. The formats need to be encoded, which requires shipping an image encoder with the runtime, and encoding the image during loading which will slow down loading times. Some compressed texture formats are also proprietary, so we're actually not allowed to ship an encoder.