Caste system has no official sanction, therefore takes a fluid form to survive. It is not true that Brahmins are mainly artists and government officers. Historically, brahmins were not just priests or advisors, they were basically custodians of knowledge of any kind. That is the reason they tend to be better educated and are found in diverse professions. With time banias and kshatriyas realised that knowledge is wealth, so they took to learning too.
Linkage between caste and profession has become weaker now, except if you are talking about very marginalized castes. Whatever caste you were born into, everyone wants to have a successful career or run their own business. This makes everyone tend towards the Brahmin (knowledge) or the Bania (business) tendencies.
Politics has become dominated by regional ethnic groups within states (not necessarily a bad thing). It was inevitable because in a democratic setup (theoretically), numerical superiority counts. Brahmins and banias have taken a back seat in regional politics (though this is a bit of simplification) because they don't have numbers to counter the numerical superiority. Now you might think that Brahmin is a caste and not an ethnic group, but in many states it is effectively that - an ethnic group. Especially in Southern and Eastern India, where the Brahmins are even visibly different from the lower castes and have different rituals and food habits.
Among urban educated folks, a career in politics is looked down upon. Some upper castes might even say that they have left dirty politics to the lower castes and occupied positions where they can have some control without getting their hands directly into dirty politics - ie. media, business (money power, crony capitalism) and institutions.
Hindutva is a different movement. While ideologically dominated by the upper castes, it needs some support from all sections of Hindus in order to overcome what it sees as its principal problem - that Hindus are not united. In that sense it must gloss over the caste system and one way to do it is to have a common enemy.