they didnt make blue subpixel brighter, they just made it larger since their life span is 2x shorter than red or green.
and it has nothing to do with bluish tint, it has more to do with color temperature.
higher the color temperature, it has bluish ton, lower the color temperature, redish or yellowish (just like colors of stars).standard color temperature is 6500k.
the reason why they made it high color temperature, it increases readability as well.
so galaxy S has the highest color temperature at around 9900k+ since its ppi is at around 200, so they raised color temperature to make up for poor readability.
for samoled HD, they lowered color temperature to 7600k, so alot less bluish than galaxy S. they did it since ppi for samoled HD improved to over 300.
about luminance, OLED works differently than LCD. since it has much higher contrast ratio, luminance on amoled works 1.5x~2x than LCD. (around 200 luminance on amoled works as 400 on LCD)