If the straddle is superior, it would have stayed superior when resistance to the flop was at its peak. I think sight throughout the jump can be a drawback over learning temporal and spatial relationships without always using sight of the bar. You still use sight in the HJ with the flop, most notably use of the opposite standard. It’s more painful to land on the bar on your back, besides most misses initially move the bar up and away or laterally away on first contact in either straddle or flop. It easier to negotiate your limbs over the bar on your back as opposed to on your front.