"A pole in the center? No floor? Unusable (for sleeping at least) inner 1 ft. perimeter, an entrance that lets in rain or snow when opened?"
If there one person on each side of pole it doesn't matter, or gear on one side, person on other. From an engineering standpoint, one pole vertical is stronger for the weight than multiple poles or a curved pole. And you get headroom for sitting erect when it's raining.
I sleep without tent about half time, so I need waterproof sleeping bag bottom anyway, tent doesn't need to have waterproof floor. And if I have dripping wet clothing or condensation on inside, better to not have floor for drips to soak in. If you have insect infestation, maybe a floor is good.
Yeah, 1 foot perimiter is unusable, so floor size has to be that much wider. If the edges are raised a few inches for ventilation, this 1 foot allows rain splash to soak in.
The 1 foot perimeter is worse when there's snow on the tent, although you can tap the snow off from the inside, but that's a nuisance.
Don't put stuff directly under door. When you open door on floored tent, rain blows in and gets floor wet.
Mids aren't perfect but good under most conditions at least I experience. Don't work so good for some people, like a couple that wants to sleep next to each other.