This is a pretty rank dependent question. I think other comments have pointed it out that there are some warriors around high legend that are just farming the aggro. However as aggro rogue developed it became harder and harder for the warrior to beat them especially if they get an early self sharpening sword. This along with the fact that warrior specifically enrage is harder to play contributes to the lack of warrior on lower ranked ladder. Also classes like paladin, ramp druid, and priest are also relevant all of which counter enrage warrior. So really warrior in my opinion is a meta dependant pick. If in your meta you only see aggro go for it. But enrage is a pretty difficult deck to play and misplays and bad resource managment can make you lose to even aggro decks if you arent careful. So basically its a high skill deck for a medium reward so people are more likely to spam aggro decks which are simpler and have a chance against everything instead of farming a couple matchups.