Talking about the SB for the fuel bladder tank to my local aviation authority about a year ago they told me that neither them nor the EASA saw any use in turning it into an AD. One year later they suddenly do.
I'm speculating, but I think the accidents in Australia might have changed some minds.
What about all those other helicopter in the world flying around without fuel bladder tanks? Our H300 doesn't have one either. Will we have to replace those tanks as well pretty soon?
The H300 doesn't have the same history of post crash fires as the R44. I'd say the size of the R44 tanks, as well as the proximity to the driveshaft and forward flex coupling are a factor here.