I found your tool PVRTexTool to be very good so far. I am in the process of adding the capability into the Babylon.js WebGL framework of being able to select compressed textures at page load, based on the capabilities of the client / device. Have standardized around the .ktx container format for obvious reasons.
DXT or BC is a valid format for Windows WebGL clients. In the tool, I think, you can just switch to a Direct X group, but not all of the BC’s map to DXT. Direct X names are also not ideal.
My idea would be a to add a WebGL group which would contain all of the items of the OpenGL ES 3 group + those Direct X formats which work, using the FourCC names. There also AT formats that work with WebGL, but not sure what those are.
Basically, all us WebGL’ers want is our own group. Not additional formats.