>Krow just has a lot of hp and can run back to aa.
THIS IS THE ILLNESS.
Vamp not being able to kill is just a symptom. Fix Krow and Vamp gets fixed automatically.
Basically, Krow outruns everything. It's faster than a raider! It goes against everything "assault unit" means. It has insane burst dps (one-shots a 12,000 HP Warlord for those still paying attention), can kill spam, and has own limited AA. It totally breaks any sort of attempt to define a role for this unit. It does every single role in the game: assault, skirmish, riot, AA, and anti-heavy. And it does them all extremely well. Except AA, which it does pretty darn well.
The worst part is that it has a limited set of (boring) mobile counters. Even the "best" AA in the game (Archangel) is still much, much slower and really serves as more of an almost-static (vs. mobile) defense vs Krows. Today Sak kept telling everyone to spam Vamps vs. Krow rush. Really? That's it?!? ZK is a game of MANY counters to each scenario, and the best Sak can say is to spam Vamps? A unit that is ONLY useful vs. other air? It's boring and reactive.
Is that the kind of game we want people playing? I can see it now:
>Ally 1: Enemy just finished Krow!
>Ally 2: Sigh, guess I'd better spam Vamps....
>Ally 1: Welcome to ZK.
Krows need to be less able to take out a huge swath of enemies in a single shot. Why not simple slow it down? It can be amazing vs. fixed defenses and poor vs. mobile units. It's ability to quickly move in, drop at 20K damage bomb, and move out quickly is simply too much.