You shouldn't be able to dodge in a 1x1, meaning you'd be missing a defensive skill entirely, though you'd gain the others faster.
If that's true, and you made 1x1 to train up legendary shield users and blockers(weapon skill)... Does that mean they'd always block and never dodge? You could train a unit of elite bridge-fighters and never worry about them falling to their dooms.
Yes, but I'm almost positive that blocking takes priority over dodging, and even a legendary +5 shield user regularly dodges, so if you remove that entire skill then your dwarf is just taking the hit. Might be okay with edged weapon users that your armor outclasses, but a blunt weapon can easily break a bone like that, and generally(in my experience) the first major injury is the last one, unless your dwarf just got unlucky and has lots of backup to clear the invaders off his unlucky near-corpse.
It's much easier to drain or floor over all the murky pools than engineer some crazy semi deathtrap to raise them to adequate swimmers that will occasionally maybe eat a dwarf. Heck, all you really have to do is channel out a tile in the side of it so there's a ramp for them to get out of, they'll get out fine as long as they aren't unconscious or missing several limbs, in the latter case you kinda want them to die anyway.
I could see wanting swimmers if you had a major river or ocean on your map, but those both slow me and my crappy computer down so much i never use them anymore.
Edit: also, you will max out all combat related stats from danger room training quickly enough as it is, swimming a little won't speed it up or give you something important you wouldn't get otherwise.
If they don't have ANY swimming skill whatsoever, they WILL drown if they fall/dodge into the water, even if there's a ramp 1 tile away
I think any depth above 5 will make them panic and drown, anything below 4 they can walk out of, or something
You need either competent or adequate skill at swimming for them to not panic if they get dumped into the water (whichever one is higher), and for some reason, I don't think they panic if the water is dumped on them, instead of the other way around *shrug*, also, they can keep fighting (training) under water
And flooring over the pools would mean giving up! It would mean that we're AFRAID of the water
We are dwarves, not some pansy elf folk