greenmaji, I really don't know why people strive for a higher K
other than the fact many have read that it is better for the corals. (this is an unsubstantiated fact)
Light intensity is more important to a coral that uses light, than the specific kelvin that the light source has, and the lower K
source has higher lumen output.
Many of the oceans corals have adapted so that many species can survive at great depths as well as in shallow waters, even though the intensity varies greatly and the kelvin in shallow waters is lower than the kelvin received by the corals in deep water.
If you really look at posting about lighting and kelvin, you may notice that many times hobbyists don't use, or do use, a specific kelvin, because they "don't like" or, "do like" the look of their tank with specific lamps and specific kelvin ratings. For these people, it's the look of the tank that counts, as it does for me.
Others perceive a change in their corals when they change lamp sources to a different kelvin, but conversely, reports are also found whereby another hobbyist perceives the same changes when going the opposite way.
Would this be because the corals, even the same species, might be from different locations, or, in my thinking, would it be because of some other unknow reason that coincidentially happens at that time.
It's also possible that when changing to higher kelvin, one might experience the placebo effect, in that one is looking for a result after making a change, and then "sees" it.
I certainly don't have all the answers, and what I believe may not be always right, but I hope I always keep an open mind to all sides of a discussion so that when evidence suggests I'm wrong, that I'm able to correct my thoughts.
So far however, there is proof that light intensity is important for coral survival, (at least for those requiring light) but I have seen no documentation that says in general, corals "require" a specific kelvin.