There's no correlation between age of a product and security. If anything the older the project and more nebulous the code base, the less likely anyone inside Adobe even understands it all. I use sumatrapdf and evince so I'm not affected personally but I think the only hope is either replacement or freeing the source code for the product. From a business perspective, Adobe will only go and fix bugs that become a big enough PR disaster that they can't ignore them. There would also need to be a viable alternative to their products.
Similarly to how Microsoft has had to acknowledge OpenOffice, at some point hopefully GIMP and Inkscape and other creative tools will cause Adobe to address their own issues. The software industry has a serious lack of competition and without free software that closely mimics commercial products, it's hard to imagine anything improving substantially in the near future.