I was reading the 4gamer interview and I read something that caught my attention with regards to why attributes have such a slight effect:

"Matsui: As we move towards getting rid of the physical level, we’re making adjustments to the underlying game formulas. However, we know the person who was in charge of them before worked really hard on the parameter allocations. For example, they worked hard to figure out how to make a character with a physical level of 50 still play in a balanced way in a class where they are ranked 1."

I think the old development team made attributes have a very small effect on performance compared to class rank. It's not that they are broken, it was by design that their contribution are nearly insignificant. They possibly chose to use this method of balance.

In that quote they also mention that those formulas will be changed along with the removal of physical levels so it's very likely we can expect that 1.19 will finally make attributes relevant.