[Sombre]

Yes but the parry is only added to defence on melee rolls. It doesn't help against earthquakes, when being trampled etc. In fact with a tower shield for example, it gives a malus to your 'real' defence value in these situations. When compared with weapons and armour, which give defence bonus or malus in all situations, the parry value from shields doesn't come across as 'real' defence.

I personally think the way it's displayed just confuses people.