There's no shortcut for getting all of the valvetrain stuff out of the way, which is required to be done before the seals can be accessed. And that's what Mazda wanted to streamline with the special tool set. Also, they certainly wanted to stay away from pulling the head (and all of the extra baggage that goes along with it), on all of the affected vehicles, which they accomplished with their tool set as well.
I believe that Mazda put together a really fine package with that set of SSTs, along with the highly detailed procedure (which includes LOTS of warnings and cautions). Yes, it took them around a year to build the whole thing, which seems like a very long time for something like this. However, I believe that's a reflection of just how queasy Mazda feels about the idea of their dealer service departments doing large scale, significant engine warranty work. And that idea is reinforced by the bit in the TSB which limits the job to Master techs only. They most likely went through lots of testing iterations and revisions, trying to make this as idiot-proof as they possibly could, before releasing it to the dealers.
And, based on the absence of negative reporting from owners who have had this work done, I believe they've successfully accomplished everything they were trying to do with this project. I'm no Mazda fanboy, but I do try to call 'em as I see 'em.