You don't necessarily have to take away features to reduce cognitive load. You can actually reduce it by adding features in some cases.
For example, I believe that adding Sum Types would actually simplify most class-based languages, because it would mean that you can use a straightforward tool with a 1:1 mapping from real-world concept to language concept for representing "or" (a very fundamentally logical construct!). As-is you have to use an awkward inheritance pattern with classes. Or use a union and keep track of the tag manually. There's an extra feature, but the usages of the feature become straightforward. It's the same principle as writing longer but more straightforward code rather than a gnarly one-liner.
For example, I believe that adding Sum Types would actually simplify most class-based languages, because it would mean that you can use a straightforward tool with a 1:1 mapping from real-world concept to language concept for representing "or" (a very fundamentally logical construct!). As-is you have to use an awkward inheritance pattern with classes. Or use a union and keep track of the tag manually. There's an extra feature, but the usages of the feature become straightforward. It's the same principle as writing longer but more straightforward code rather than a gnarly one-liner.