'Additional data might be necessary for complex financial transactions'

I tend to disagree with that.

I think Bitcoin was born from the intent to build a money transmission system. And it should be as simple as possible so it can be as efficient and fast as possible. All the other things and data can be build around it on things that are specialized for their own purposes.

Building specialised systems for different purposes that can work together to create something bigger than the sum of the individual components is basically what we humans are doing all the time.

A 'do everything at once' system couldn't be scaled to millions and billions of people.