1. Stupid meta sheep who flock to whatever the pros play, with no idea how to properly utilize them or even why they're being played.
2. He's popular again for the same reason as when he last made an appearance up in the professional scene: his bloody ult.
Riot, please, if you find yourself looking at Vladimir again, take a look at his ult and how it functions, rather than slashing the values on his basic skills as you did before. Maybe the AoE % damage amp is too difficult a mechanic to balance altogether, and warrants scrapping. A while ago Reav3 mentioned that he'd like the VGU team to tackle Vlad someday, but that was far into the future, maybe he needs a small Shyvana-level rework to Tides him over until that day comes?
If his ult is the reason that he's such a bipolar Champion depending on what level of the game you play, that's what needs to be looked at.