Hexes were rolled into conditions so players could distance themselves from the build wars. With the unified conditions/boons system every player can have a response to effects applied to them. This allows players to play solo with every profession, exponentially increases the number of viable individual and team builds, allows for long-term combat, and shifts the strategy from having the right build to using the right tactics. It's an improvement in every way if you want varied and balanced combat. Hexes just don't fit in GW2 in any way.
Hexes were part of a "rock-paper-scissors" balance system that had to many categories that lead to imbalance. There was all the "normal" categories of combat and then hexes and hex removal were separate, making them easy to remove (one of the first major changes we knew about GW2).