probably designed for the majority of passengers, not all.
6'4" is like the 99th percentile so you might be out of luck.
and I can just see people of short stature using this. or children?
Maybe if that was a five-point harness, but... that looks like a single buckle between the legs, probably two over the shoulders? That's not holding a kid in place, for sure.
I'd probably like this better to be honest, so long as they make the compartment tall enough. I'm 6'4" and my experience flying was that the overhead storage was too low.