I think this goes against some of the principles Bitcoin was built on (namely, anonymity). The best thing to do is, if someone is really afraid that their Bitcoins will be lost upon their death, that they should take it upon themselves to individually ensure that they won't be lost. A lot of people are already doing this.
If we were to look at this collectively, I don't think that losing Bitcoins hurts Bitcoin itself. It's value grows the more scarce it gets. But maybe people would be able to tell us more in about 50 years or so.