As with all economics, the answer is probably complicated. Death incentives aren’t great. Brands partially have value because they can be kept consistent, and some iconic characters have kept a relatively consistent identity across multiple authors. Allowing a free-for-all too early might make those kinds of characters harder to develop?

My favorite variation on this (which probably also has complicated consequences) is that government should, after say ~10 years, get the chance to buy any particular copyright/patent for a sum (based on its profitability, say), and should they choose to buy then the work enters the public domain early. No idea what horrors this hides.