Official reason was certain batches snapped on loop knots, they spent hours on the DVDs telling people to tie them and...SNAP!!!
They brought out the stiff as a replacement which IMO is nowhere near as good, ive got half a spool of soft left and ill be gutted when its gone. I ALWAYS use loop knots and ive had no bother at all, some people did though. There is a point where the manufacturers have to recall products if there is an obvious issue, not a one off. It will be calculated in percentages and cost effectiveness i imagine.
Cant you remember the last DVD??? Mr Fairbrass told people to use the little rig rings instead of loop knots, he never shut up about it!! Clever really as it means you will go buy the rig rings now even though the stiff is fine with loops.