Why is LastFM disabled by default?
This choice means that probably most distros don't have this support and means that Music can't provide the support for it as a result (unless they ship their own implementation, I suppose).
Most users won't build their own so it means that this support is effectively unused unless the distros make sure to enable it (which Fedora doesn't, for example).
So really, I'm just asking to provide this by default to ensure that people can use this..
CC @jfelder