I don’t like the flat penalty because Science is so important and there’s absolutely no control over that. A Dark age shouldn’t have to be tied to Science alone. It could relate to your military, or your culture, or even your religion and economy. The Great Depression could be considered a kind of Dark Age, but it had everything to do with the economy. That’s kind of why I went with the policies, to “choose” your kind of Dark age like you’re telling the story, and you use that choice to recover at a cost.
I think Dark age policies shouldn’t be built into the dedications and I find the dedications filling their functions appropriately (a means in non-Golden ages to gain era Score). It would be okay IMO for dark ages to work a bit differently by utilizing these policies better and integrating the more. As of now, they’re an optional sideshow that I don’t really find particularly attractive, and Dark Ages should be less attractive, but not necessarily only because of a Science penalty.