After the artist dies, there's no reason to "support the artist" anymore and while there is the effect of post-mortem sales spike, a celebration of now freely available music for all to enjoy would be a much better hommage.
As for the family, there really isn't any reason they should obtain that copyright. If they wanna earn money with art, they have to create art on their own. What the current laws create in most cases are lazy rich children who spend the rest of their lives managing the copyright legacy of their parent. That doesn't benefit society in any way. Either they work like normal people or they make their own art but they're not entitled to the copyright of their parents. If the parents don't want to leave them in poverty, they can still leave the money they earned with this copyright over the years for their children.
Also, with the minimum 50 years duration, they could still inherit the copyright if their parent dies at an early age. However, a term of life PLUS a ludicrous amount of years is a really bad idea for the cultural development of our society.