Are the rear windows suppose to go down only half way?

Not the dumbest ever (maybe close) And yes, they only go down halfway. It'* a "Safety Feature"

I thought it was the way the door was designed?

No! If they admitted to that, they'd have to admit to the way they designed the upper intake. It'* a "feature"....

Same here.

But I guess a safety feature for children in the back would also make sense...

Damn I was hoping the previous owner just flipped a safety switch that I happen to not know about

IT IS NOT A SAFETY FEATURE If it was a safety feature then all cars would have rear windows restricted at half open. it is due to the curve on the back of the rear door allowing the wheel well to be where it is, if the wheel well is set further back they could and maybe would have made them roll all the way down.

In the manual it says "safety feature"

I love how they market it as a safety feature although it was just a consequence of design. The GA goes down *almost* all the way (like with five inches showing) but still runs into the same problem.