cout << "Hello World";
It looks like they did that just because they can.
The thing is, people thought it was a good idea at the time, and had good reasons. It took maybe a decade before experience showed otherwise. Even today it takes a while to convince newer programmers that it is indeed a bad idea, and even then they don't really believe it.
An even more perniciously bad language feature is macros. I'm pretty sure that once I step down as D's BDFL or am forcibly removed D will get macros :-/