You make the skill sound more powerful than it actually is. There are 3 important things to note about the skill that must also be considered.
First: The skill has a long CD early game. This in combination with the HP cost of his E means that he can't bully everyone out of lane. He's strong against other champs that just want to poke you done since Vlad can counter poke and out sustain them. But against champions that like to burst combo and all-in you, Vlad will lose.
Second: The skill is only half his damage late game. Vlad's E is extremely powerful late game and even for single target bust, it will have as much damage as his Q. It will also covers a large portion of his HP regen through its own passive, spell vamp and AoE
Third: The range on his Q isn't that long. Its a little longer as his auto range. This means that he will usually be within engage range. So unless he wins the match up (I.E. against poke) he endangers himself if he tries to move forward to poke. It also means that he puts himself in danger during pre-team fight sieges and may very well be the one that gets caught out to allow for the team fight to break out.
Your description makes him sound like a Xerath who can't miss with infinite sustain. But he is far from it.