Because the competition season has been extended to 6 weeks for at least the last 2 years, that pretty much limits when kickoff has to be. Else you're pushing the Championship into May.
This year it would have been nicer if kickoff could have been Jan 10, simply because many schools didn't open up after break until the 4th. But it wouldn't fit into the schedule - Atlanta is scheduled more than a year in advance and can't be moved. Unless you want a 5-week build ...
edit: I just looked at the GWCC site, and FIRST is scheduled for the same week in April for 2010. That likely means only 5 weeks of competition next year.