It's kind of done on purpose, of course, it almost seems like Erikson makes a point of putting at least one revelation and twist casting a new light on the events of each previous novel, in every new book he releases. It certainly makes the series more interesting, and induces people to re-read, but it almost seems like a gimmick. My last re-read of Gardens of the Moon must've been somewhere around the time I read Midnight Tides or the Bonehunters; since then, my reading Reaper's Gale, Night of Knives and especially Toll the Hounds has added still new things that will have an effect on how I interpret things in Gardens of the Moon.

I do wonder whether my decreased enjoyment in the Malazan series in recent books is because those books are really less good, or merely because things get repetitive and one gets the feeling that nothing really matters in the end. Toll the Hounds is probably a better novel by far than Gardens of the Moon, considering the oft-discussed jump in Erikson's writing abilities from GotM to DG, but I have a feeling rereading GotM would be more fun for me regardless.

As for the Bridgeburners, other than Whiskeyjack most of them at the time of GotM had little distinct personality, at least for me, and that made them less interesting. The fleshing out of several of them - Quick Ben, Kalam, Fiddler, Antsy, Blend and Picker, probably more I'm forgetting now - later in the books ought to make their scenes in GotM more enjoyable. So it doesn't surprise me that you like them more this time around.

On the other hand, I think if I reread it, my annoyance with the exaggeratedness of "Kruppe is a genius orchestrating everything" from Toll the Hounds might carry over to the lesser instance of the same thing in GotM, and same perhaps with other things (Erikson's rather dubious moral observations on bullying children and the like from that same book).