I think part of the problem, is that if you haven't been watching from the beginning, you miss a lot.
This is definately the right time to start watching, as this season is basically a restart.
I think tv producers are wising up a bit. Shows that have an intergrated narrative(ie. Each show starts where the last left off) have a much better plot. BUT, the problem is atracting new viewers. If the plot becomes too involved, then new viewers tend to stay away, as they won't understand what is happening (or, ie. if you miss an episode, you're screwed)
That's why I think this '2 year' restart has occured. To attract new viewers, while disposing (not fully) of the last two seasons, without hurting the plot