It's less a problem about superpower/magic and much more about willing suspension of disbilief (there's many superpower/magic shows I enjoy, I'm a mahou shoujo fag to boot... a guilty pleasure of mine, I suppose
). The setting seemed to be very realistic to me, but then we got hints of supernatural elements which I thought were unfitting to the show itself. So yes, it's not like I automatically dislike superpower/magic animu, it's just that I thought they didn't fit in here. But overall the show took a direction that wasn't to my taste.
There's people that like it, I know, that's fine, they did this side-story for them. I'm sure fans are happy and appreciated it and I am glad for 'em.
But Saki just wasn't what I was hoping it would be, my own fault for searching in it something that it wasn't trying to be. Doesn't mean I should like it for what it is regardless, though.
I'm not the first to be hating on Saki either, though I'm quite aware of the fanbase. Still isn't my cup of tea for various reasons. That's about it.
Re: side-story: that's really what I meant to say, I just didn't find the words to express it, so I went with "spin-off of sorts" to say it. It indeed is a side-story and not a spin-off, though, yes.