As I work my way through Harry Potter and the Order of the Phoenix, I notice two particular themes.
The first is the abuse of power. Dolores Rose Umbridge (she who gives sorrow and umbrage?) is the prime example in Book 5. She delights in lording it over others giving sorrow and pain as often as she can. Although her power may be in order to serve the Dark Lord, she seems to delight in using it for its own sake.
Draco Malfoy (Dragon->Snake Bad-Faith) has been intimidating others from Book 1, just for the sake of showing he is superior to them as a "pure-blood" wizard.
Snape uses power to avenge the ill-treatment of those who abused power when he was in school. But so far, we aren't aware of his turning on his abusers, just passing the abuse on to others. Do unto the new generation as the old generation did unto you.
The giving and taking points to and from a "house" in general is arbitrary power. The many gain or suffer from the actions of a few. This power seems to be exercised by whim, whether a teacher wants to give praise or wants to punish, punish, and punish.
The second theme is that power is not all-powerful. Despite all the miraculous, wondrous things the wizards and witches can do, they don't seem able to make the plumbing work and a whole lot of other ordinary things. Carpets are threadbare, ghosts pull pranks on the students, and buses don 't even have fixed seats.
I may be bringing my own bias in, but I think J.K. Rowling is calling for society at large to spend more time on governance than posturing. Rather than showing we are a superpower or that we are not going to knuckle under to the developed countries or that we have to be sure our group gets a bigger "slice of pie" we should just make things work for as many people as possible.
