The improper sorting, to me, is a much bigger deal than the forced 100% export is ever going to be. I really hope the wheels are turning on some way to correct this and make these songs sort under their proper heading in Rock Band 2. I can't imagine the Rock Band 1 community being too vocal about Lego not exporting into that game. While I understand that some places outside the US still don't have Rock Band 2... isn't that a bigger problem than Lego going into 1?
I can't see a whole lot of very good reasons it was handled like this and I really hope HMX has some kind of plan to correct it, either with a patch of some kind to Rock Band 2, or something in the inevitable Rock Band 3.