I just saw the caption under the pic in the link. I live in Jalisco. Those bats are quite common here and a threat to cattle but we never heard they attacked people... Bees and wasps on the other hand... *shudder* Nasty vicious little creatures.
I'm a big fan of chiroptera, so I admit I'm extremely biased about them.
They seem to be getting more avid about attacking stuff you wouldn't normally expect, from all reports I've found. Are cattle farmers giving up on the area and taking away an easy foodsource? There has to be some reason for them to be picking a hard target, preywise. They are vicious little creatures, it's true. Their saliva glands also produces some of the most powerful anticoagulants known to mankind, which has produced remarkable strides in medical means of dealing with cardiac issues, as well as surgery: it's quite possible that I wouldn't be here without some of the research they prompted. Vampire bats are also a completely unique chunk of the mammal order, which subsists on a foodstuff that's plentiful- yet inedible to most mammals. There's a lot with them that we could learn- provided we don't screw up the planet so bad they're no longer there to learn from.