The music is licensed by the record company. If a distributor wanted to release all the episodes on an official home media (streaming, blue ray, etc), they would need to pay for the rights of the music. Each. Song. And they are all hits so that’s big money. The cost to license this music would outweigh any benefit of release the home media. Hence the issue, no one wants to go through that headache. It won’t be resolved until the songs enter the public domain (70 years minimum).