I would hazard a guess that it is because the statement allows for easily adding a `print varname` in your code while debugging.
It's two extra chars to write print(varname). One if your editor auto-inserts matching parens!
Since the space is replaced by the first paren, it's either 0 or 1 more chars :)
Shift-9 is more fiddly to type than space though :P
print(varname) is one extra keystroke -- and a whole more convenient than a statement when you want to do it in a lambda for debugging.
That's why I'm asking really - not only those two would be pretty much equivalent, there's really nothing that can be expressed with one, but not the other. I mean that's kind of like saying "would you use it if they called the binary snake instead of python3" - what's the reason apart from personal preference for the syntax?