Being a good build and being an easy build are not related.A monkey could beat a turret with 4 B's.Yes, it takes skill to fly a turret well (and win), but not as much skill as someone who doesn't take a fat turret and wins, especially against a fat turret.
See how easy it is to just say stuff.
Easy to say things, like: "turrets take a lot of skill", but results like the Regionals point towards a lot of truth about turrets.
Hodge-podge. An "Easy" build can contribute a number of factors that can also help the build be "good". Less mental drain on the player. More forgiving of mistakes. More able to focus on future turns rather than just the current one. Less factors (such as arc) to consider.
While being "easy" doesn't necessarily make a build "good", and all "good" builds will not be "easy", there is certainly a positive relationship between the two. If two builds are equal in firepower, durability, maneuverability, etc with one being easy and the other being hard, the easy one will be at an advantage for the reasons I've listed above.
Easy doesn't necessarily equal good, but they are related.