I've ridden in as low as -5c before windchill, on the highway for a couple hours. Exposed flesh is an issue. Appropriate gloves is the highest priority (Revit Kodiaks are what I finally settled on). Underarmor Base 4.0 was enough for me, no heated gear needed, but it is not appropriate office wear so a full change is needed both to start and end the day.
Also, you have zero grip till the tires 'warm up', or what passes as warming up in winter. Also, slush and actual snow is not happening on street tires.
Motorists also seem to totally forget about motorcycles on the road during winter.
To sum it up, commute is not worth it, but you can definitely get some riding in on those sunny dry winter weekends to scratch that itch.