I think they should port over only the first 6 games. That could easily be done with little effort. Seeing as the GBA is around the SNES in power it could easily support games like FFIV and V. I'm actually surprized that Nintendo and Square haven't even done this already it would sure bring in some money and make everyone happier.

OOC:
Lunar Silver Star Story (PS) was ported to the GBA as Lunar Legend and its exactly the same.
A bit off topic, but I have Lunar Legend and it's got quite a few difefrences from the PS version, namely some bosses and plot points were taken out due to lack of space, this makes sense seeing how the PS version was 2 discs, which is quite a lot more then any amount of memory the GBA has.

Ya just thought I should mention that.