The whole "tweeter at ear level" thing is overblown. Just sit at a height where it A: Sounds good to you and, B: Presents a deep and largely horizontal soundstage. This is speaker dependent. I sit with my ears a good 12-20 inches above the tweeters in a near field arrangement and everything's splendid.
It's possible those designers are placing the tweeter underneath the woofer to provide a warmer and more coherent sound when listening on-axis, with the woofer at ear level.
It's possible those designers are placing the tweeter underneath the woofer to provide a warmer and more coherent sound when listening on-axis, with the woofer at ear level.