Okay, so we mostly agree that a sequential, time-based autonomous is extremely easy. But that doesn't require any sensors. Why are sensors useful?
Sensors increase the repeatability of an action as other factors change (e.g. battery voltage drops or mechanism gets jammed) Sensors also allow the robot to respond to changes on the field, meaning the robot can operate based on intent rather than actuating by rote.
Higher levels of control are useful in connecting actuators to sensors in common and easily configurable ways. For example, in NXT-G, it allows you to tell the robot to go forward for a time, a distance (degrees), or until told otherwise. It even allows you to ramp the speed from the current value to the desired value. Likewise, the "wait" function is configurable for a time, or until a sensor is greater/less than a given value. Such high-level coding can save time and reduce errors.
As has been pointed out, all robots are different. Such high-level control needs to be extremely configurable to allow for the differences in sensors, strategies, decision making, actuator control, and wiring configuration.
In other words, it needs to be modular and extendable. I like the idea of separating it into
Perception,
Planning, and
Control. (Linked are Chief Delphi threads about each one)