They should be, IMO. Because the Panthers lack a bunch of big-name players at skill positions, and because Newton isn't as established as Brady was, people aren't taking them as seriously. Also hurts their case that they their passing game isn't consistently flashy, although it sure has been for the past month.
I will say this: the Panthers right now are a better football team than the '07 Pats were as of week 15. The Patriots were starting to wear down at this point, and were getting hit by a couple of key injuries. The Panthers seem to be peaking, and have been remarkably lucky on the injury front. It'll be interesting to see how they handle Jonathan Stewart getting hurt; if CAP comes in and dominates they might just be in team-of-destiny territory.