I don't really agree with the suggestions of Arriva overusing their brands. From a customer point of view, I think James101 has hit the nail on the head, the three brands are categorising services so customers know pretty much what each service does. From the point of view of Arriva, the brands are growing passenger numbers and therefore increasing income, leading to the potential for more investment. 

I think, generally, comparing Arriva and GNE branding is like comparing apples and oranges. (I know I compared Frequenta and IndiGo earlier, however from what I understand they serve a similar purpose). Arriva have branded routes into categories, whereas GNE went for an approach of branding anything and everything with no clear structure - bar IndiGo.