Like tons of people said already the attacks on villages are really rare and guards do a pretty good job at taking them out if you are too weak or slow to do it yourself if you can't do it yourself then I suggest the first thing you look for are the time slow shouts so you can take them out easily and fast.
That completely depends on your level and just how lucky you are. (Here come my 2 cents)
On one character (level 62, pretty OP), I've visited whiterun 6 times since the DLC started and had a vampire attack three times.
At this level the guards are still pretty capable of taking them out, but villagers will still rush in and who the vampire chooses to attack varies. At higher levels these guys will 1-hit damn near every villager, and one of the times I had to reload it was because right before killing the last vampire he casually turned around and ice speared an attacking villager in the face. It's not hard for them to kill NPCs.
This is the issue. Even though I know that a lot of people have experienced this less than I have, that doesn't change the fact that it's still happened to me and a fair number of others. I would never consider these vampires a threat to me personally, and even if they took out a guard I wouldn't care (guards respawn anyway), but when I visit a town I don't want to have to worry about saving all the villagers because a random vampire might show up. That's the kind of thing that makes the experience seem like an annoying
chore.
These are actually way worse than dragon attacks too. At least those attacks are extremely rare in walled cities, and dragons attack much more slowly and predictably. Dragons (like other AI) will generally go for whoever last attacked them when they're in a town, and %99.99 of the time that's a guard with a bow. This makes them much less dangerous to villagers and easier to handle.
Now if these attacks were better scripted and were more or less unique (instead of casually spawning some vampires next to me when I walk through the door every now and then), I would not have a problem with it. Even if they added vampire ambushes when I'm out in the forest I would be ok (in fact that would be badass). But instead what I've got now is vampires that will attack pretty much the first thing that gets their attention (which often isn't even me).
But that;'s not even the majority of the games. That's just yours. The whole damn expansion isn't like that.
Of course not, the expansion is [censored] awesome. But this is really annoying for a lot of people, and to say that it's ok because it's more rare for you or because someone exaggerated their story is silly. Whether or not someone exaggerated their story is
completely irrelevant because you don't know how their playthrough went and especially because it's
still happened to a lot of people. Unless you work for Bethesda's PR or advertising it shouldn't even matter to you. Of course you can share the fact that you didn't experience that crap and you found the whole thing to be great, but you shouldn't try to undermine other players' complaints with the justification that "some of them are just exaggerating!".
The DLC was great, not perfect, but great. However the vampire attacks that it brings on can be significantly damaging to the towns and therefore the player's experience. Though it's not a problem for everyone there are a sizable number of people who are frustrated by it. It should be dealt with.
There you have it.