[pmilot]

Others have brought up good points, but I'd also add that the ad-hoc solution only supports calling methods on possibly-null objects. If you want to pass a possibly-null object to a function that does not accept null values, only the monadic solution works.

In fact, you can see this in the example. AFAIK, the ad-hoc example will end up printing a null value, while in the monadic example, print is never called at all.