Elemental Resistance: Why Even Have It?

[Felis]

Ok I did a quick google search and found this:

This is about elemental wheel, but we discuss about elemental resistances.

"This enemy is ice element, attack it with fire for more damage and don't attack with wind" - elemental wheel
"This enemy is strong against fire, attack with all what you have but not with fire" - elemental resistances

During beta Yoshida wrote why he think that elemental resistances is better than a whole elemental wheel