Hard to tell where the sarcasm starts and ends, so my apologies if I am taking you too literally, but my assumption would be that we haven't seen 'serious study' of penis enlargement because it's highly unlikely there's some simple way of making it happen, especially one that doesn't also have side effects...
There's an old joke that penis enlargement is very easy through mechanical means, it just doesn't last all that long and leaves a small mess at the end.
