There are tons of relatively cheap music libraries with human-composed and human-produced music that is vastly higher quality than MusicLM's output - they are used for documentaries/commercials/low-budget projects and are loaded with metadata that make it easy for directors and editors to quickly find what they are looking for. Low-quality, weird-sounding AI-generated music with wonky rhythms, an inconsistent beat, bizarre digital artifacts and a generally unpleasant lo-fi sound that probably has to be patiently generated and listened to over and over again to find a usable result is highly unlikely to beat out already very cheap, much higher-quality and easily searchable human-written music for even the lowest budget projects.
These models are still in their early phases - If AI was combustion engines, we wouldn't even be to railroads yet. Despite that, they're still fun to play with and useful when used correctly.