The FR-S is a rear wheel drive light car, is it not; with a lower proportion of weight over the driving wheels. Nice car and I like it but not the best configuration for winter traction. The all season tires would have pulled it out probably, if it were FWD.
I don't know how much of an improvement...say ice tires...would be in a similar situation of deep snow. Maybe a couple of sacks of cement over the rear axle and keep the gas tank full.
All Season is not marketing hype. Before the soft rubber siped ice tires were developed, the 'All Season' became an option to having summer tires and switching to winter 'nobblies'. When radial tires became the norm they were found to be quite acceptable with FWD cars; knobblies not offering much inprovement. This in a time when getting going was the important winter aspect; not driving at higher speed in icy conditions. From reading this thread one wonders how much better, if any, a set of winter tires with a few years of use on them...would be than a new set of good all season with a good (for the class) snow rating.