Hard decision whether to mod this or comment, so I chose to comment so I can correct the erroneous information here.
What you wrote is ABSOLUTELY INCORRECT. Intellectual property and intangible assets are absolutely part of one's estate (and also come into play in divorce proceedings, for that matter -- See the divorce of Tom Clancy) and are recognized as such under the law. If you disagree on a moral level with this practice, that's another matter, but to state that "it is not part of an estate" is spreading misinformation. I work at an IP consulting firm, and we are frequently asked to value intellectual works for use in estate planning. These can range from rights of publicity, to copyrights/copyrighted works, to trademarks, among other assets.
You say that "to consider intellectual works part of an estate diminishes human capital and is an insult to those who created it." I think you have this backwards. When the esteemed playwright George Abbott died, for example, his estate was left with the rights to his many copyrighted plays, which could then earn them royalties on performances. Similarly, after Marlon Brando's death, the demand to use his name and likeness did not immediately disappear. His heirs controlled his rights to publicity and had the power to decide when it was appropriate to use his voice or other personal aspects to endorse products for a fee. Don't you think that Marlon Brando would have wanted his legacy to continue to provide for his loved ones? Wouldn't it be more of an insult to George Abbott (whose "human capital" is at issue) to have his works just be taken away on the day of his death instead of allowing him to build something that could continue to benefit his family?
Copyright law may be totally frakked in its current iteration, but that is a completely separate issue. The fact is, people work to build an estate -- but this work does not always take the same form. Some people build corporations, invest is stocks, or gather cash; others create works of art. You would never just assume that a corporation should automatically become public because the owner died, so why should that novel or that play immediately lose all of its value to the owner? Somebody spent their life working on that (instead of pursuing other avenues of wealth accumulation) so those assets are what they have to pass along in their estate -- Or should everyone just give up creating original works to pursue entrepreneurial or big business goals so they can provide for their families after they are gone?