Why is there a need to disable enter keypress to submit form?

Some sites that has long forms are understandable.

It bothers me that some site that only have a simple login input, e.g. http://ift.tt/1DIRAAj disable the enter key when you only have ONE field. It's so counter-intuitive and frustrate the user. They even explicitly state that you have to press the button. Is there a specific needs for this? I don't see any, even from security perspective.

The fact that it's a banking site doesn't even matter. Other banks just works fine. Is this just a poor workmanship or there is a legit reason behind the decision?