I assumed it was something to do with burnin.
I.E. on amoled, black means the pixels turn off, so if you do the one-handed operation a lot, you'll quickly see an image burnin. with blue, you are using the largest of the subpixels, so maybe its a hue of blue to better handle battery drain (larger pixels need less power to illuminate to a certain percent, or there are fewer blue pixels than green, so less power needed to power, etc. could be a variety of reasons around the hardware alone).
I just figured there was a reason why it was a soft blue, and non-changeable. But then again, it could also be a simple matter of something that slipped through the cracks and wasn't even considered as an option people might like to customize.
My trek through cellphone history:
Nokia 252 - Green
Mitsubishi Trium Astral - White
Samsung Omnia II
HTC Desire Z
Samsung Galaxy Note 1 - 16GB - White
Samsung Galaxy Note 3 - 32GB - Black **Surprisingly, under warranty, they even fixed the physical damage I caused. Go figure...**