Although folks these days sometimes complain about Hollywood's love of remakes, remaking films is certainly not a new thing. In fact, in the 1930s, films were sometimes remake as few as 2-4 years after the initial movie! In many of these cases, we're talking about B-movies and obscure productions...but occasionally they remake big films...films that were just great originally and had no reason to be remade at all.
A great example of a film that was originally great but got remade anyway is "The Lady Eve". Preston Sturgis wrote and directed it and the movie starred Barbara Stanwyck, Henry Fonda and Charles Coburn...and it was a classic in every possible way. Yet, oddly, someone thought it needed a remake...which they got to 15 year later.
In pretty much every way, the remake is inferior. While Mitzi Gaynor was fine, she wasn't exactly Barbara Stanwyck. But much worse....instead of a nice-guy actor like Henry Fonda, someone thought that bumbling, nerdy George Gobel would be great in the lead...something that simply defies common sense. How nerdy is George? Well, he's an ichthyologist (he studies snakes) and seems more like Harry Langdon than Henry Fonda! He's just all wrong...especially since the film finds Gaynor's character falling in love with him for no clear reason. Even worse is casting David Niven in the supporting role. While he was a wonderful actor and great in leading roles, here he simply isn't at all in the same league as Charles Coburn...not even close.
The bottom line is that "The Birds and the Bees" is harmless entertainment...but hardly any sane people would consider it a classic. "The Lady Eve", on the other hand, is a magical film that you simply must see.