What is the technical reason for not allowing to optimize those properties?.If I use those properties in a report definition it gives a warning, that means I need to justifiy the warning is that the way?
This limitation has been introduced deliberately, so that administrators are absolutely sure before making any changes to the Pega shipped classes. If you still would want to optimize them, you could create the columns manually for the corresponding properties.
And, if you use unoptimized properties in an RD, it would give a warning. You will have to justify the same.