Facebook is launching a stand-alone photo sharing mobile application. This comes weeks after the social network bought Instagram for a billion dollars.

Someone please explain to me why this makes sense.

Here’s why I ask. Instagram, after its 2010 launch, quickly became the most popular photo sharing application on mobile devices. After the acquisition, many users feared that Facebook would ruin the Instagram app. Until now, Facebook has left the product alone. That was a wise move.

And now comes along this new mobile app, called “Facebook Camera.” In almost all aspects, it’s an inferior product to Instagram. The interface is clumsy; the filters are not as good; the product feels like something someone developed long before Instagram and was crushed out of existence.

Facebook should leave Instagram alone, but allow existing Facebook users to log into Instagram using their Facebook login. Some folks make the argument that Instagram users don’t want Facebook users on the Instagram network. I think that this is anti-social. Remember this: Instagram never wanted to be the cool indie band you liked before they became popular. They always wanted — and still want — to be as big as, or bigger, than Facebook. To appease these people, perhaps you decide to use Instagram in a “Path”-like experience, where you allow only people you want to view your photos by making your profile “invite-only.” This is already available on Instagram so I don’t so what the issue is. Path is a competing photo-sharing app that is banking on people only wanting to photo share with small groups and not the general public.

Facebook had easier options that it could have considered beside launching its own mobile app. Yet it pursued that path. Producing an inferior product must have cost money and certainly must have taken time to develop. Even if the app were developed before Facebook bought Instagram, it would have been less damaging for Facebook to pretend that it had never existed than to confuse the marketplace by introducing two competing products from the same company.