I would welcome a decrease in traffic, but I would not take stock in your sample set. The reduction is likely due to holiday/vacation events. Ironically, CalTrans has plans to actually widen I-5 from around the 805 merge to the 76 in Oceanside (something like that) to 8 or 10 lanes each side!

I am all for growth, and I work in engineering, but I do not think this is the smart way to grow. Not only will it put us another step closer to becoming another Los Angeles-type city, it will also displace a lot of residents and businesses.