I think that the same question can be asked about Mechanical ( and expensive ) watches against Quartz ( and very affordable ) watches.
Why do we buy Mechanical watches, when Quartz Watches offer us the same, I mean ..The Hour?
Why even buying a awatch when computers, cellular phones, even cars give us the Hour for free???
Just because we are attracatred by the uncomparable " poesie " of a mechanical movement, by its quest of perfection, of accuracy, of reliability, as we, Human, want to reach the same things, the same goals.
For the same reason you want to gift yourelf with a nice pair of shoes, a nice bottle of wine, or a nice car...
A Diving watch is more than a watch to dive, a watch is more than a watch, this is a way of being.
Best.
Nicolas