For every Stephen King that has a massive following and would easily earn enough in those 10 years, there's 100 mid-tier and lower-tier creators that need any income they can get from works still earning in some fashion.
Also, think about how a 10 year limit would be used against creators by the Disneys of the world. "Well, damn, we don't need to arrange a movie deal with King... we'll just wait 10 years and a day and then make a movie on this book."
Hey, indie band that still scrapes by on royalties and touring? The minute your best-selling album is 10 years old, it's going to be repackaged and sold without you seeing a dime.
Yes, it's more complicated than that, but... an arbitrary 10 year limit wouldn't fix things or make the world substantially better and might make things worse.
Now - I'd be willing to talk about things like drastically shorting terms for works for hire/copyright owned by corporations and not individuals.
We might also need to think about not having one term for all things. There's no reason the copyright term for software should be the same as that for a song or a movie or a book. Books, songs, paintings, basically art should probably have a copyright term in the 25-50 year range. Certainly no longer than 50 years.