Of modern language features only generics are really useful.
As it is really boring to copy/paste the same code just to create a hash map with different key/value types.
From the other side, in Delphi generics are achievable without language support - there is an include-based approach compatible with older versions of Delphi and FreePascal.
So I wrote a library with generic collections and algorithms based on the approach and have no need in a language support of generics.