I don’t think SG-1 started off as rough as, say, Star Trek TNG did. They were making overall good television even in the first episode of SG-1.
The first two seasons especially had the Torchwood problem of trying to be very emphatically a show for adults, which is why there’s that infamous full frontal scene in the pilot episode. I think they realized that there’s money in syndication on basic cable so they produced most of the rest of the show to kind of a PG rating which stabilized the tone.