Personally I feel like those descendants or whatever should just write their own music instead of profiting off of something they didn't do, but I don't think that view is going to find much favour for as long as entertainment and media companies spend billions lobbying governments for stricter intellectual property laws, lol
By that logic, when someone dies all their property and assets should be distributed among the public. After all, that persons children wouldn't have bought the house they live in, or earned the money in their superannuation fund.
If I were earning royalties for anything and had children, you better believe I would want them to benefit from my work after I die. And I would be mortified if anyone tried to steal that from them.
How about this for an idea? If you like something, then you should buy it. If you don't think it's worth the money, then don't buy it and move on. But don't complain because it isn't free. You complain about descendants profiting from something they didn't do but, believe it or not, that is exactly what you are asking for for yourself. You want to profit by not having to pay for the things that you want.
(Sorry about the rant. As you can probably tell, intellectual property laws are something are feel very strongly about.)