@RafiXI'm sorry that your Micro broke :/
I always considered the Micro to be more on the "gimicky" side of things. It's nice to have but not a must-have (the covers are cool nonetheless. They always reminded me of the stickers from Nintendo Power)
About the GBA design part: It's mostly because the whole device is wider. I have fat fingers and average to large hands. The best combination for a pocket-sized device