I was reading Matthew 1's geneology this morning.
One point that comes to mind is that this liniage is not from the priestly line. The writer of Hebrews makes the comment that Jesus' high priesthood is of the line of Melchizedek, who comes out of nowhere (well, out of Salem) to get a tithe in Genesis 14.
Jesus doesn't come out of nowhere, He comes from the line of David. He starts out as ruler stock, but His divine nature will also allow Him to become the sacrifice to end them all. He doesn't need to be a stanard-issue priest, for He is the sacrifice itself.