Why would kids from the North not love the water? We are in Minnesota and my parents are on a lake, my kids grow gills in the summer - and are in indoor pools in the winter. Mine would rather spend the day at Typhoon Lagoon than at the Magic Kingdom.
The thing with SAB is that its a strangely laid out pool. It is referred to as a "mini water park" but I'm not sure how accurate that is. It has a slide - as do all the other
DVC resorts. What it has that the other DVC resort pools doesn't have is a lazy river. It also has some kid slides and zero entry. And the sand bottom. The issue is really that the lazy river wraps through the middle of the pool and that there are more nooks and crannies than average - some of them with jets to bubble or make currents, making the layout difficult for anyone wanting to keep their eye on kids. Where the "mini-water park" description would disappoint my kids - they expect a wave pool at a waterpark and more slides.
The sand bottom itself is tactilly different enough to drive a lot of kid's dislike for the pool. If your kids don't like the strange feel of the "sand" they may not like the pool. The other thing that some people find disturbing is the rather sudden depth changes - the lazy river is deep - and only yards away from the zero entry area (personally, if the lazy river were three feet deep, that would fix a lot of my issues with the pool right there).
Another factor is that the slide is enclosed and tight for much of its trip. While some kids love sliding through a tube, other kids have a preference for the open slides. And getting to the slide is a walk compared to most resorts - repeat trips down the slide take longer for a kid wanting to do the slide over and over again - its way more efficient to do the slide over at BWVs.