You DO need a study to understand this. Humanity's track record with 'you don't need a study' isn't exactly stellar.

If you don't study stuff like this, your models of the world won't update on 'obvious' things like geocentrism or spontaneous generation.

The last century saw enough of these rationalizations for human behaviour - they miss the mark more often than not.

Now for why they decided to use facial expression software on the other hand...