There is no relevance to compare sky and krsna body. then u can simply go on saying some fishes in the sea are blue like whales, dolphins do u find any relevance to why hes portrayed in blue.
I think and the word itself means 'black' then he should be black, in our culture black color is always looked down. so how can a hero be 'black'. if may tel that hes god so he can take any color, its can never be that, if hes born as a human he should be any of the color that human, if hes born differently i believe he would have be outcasted. he must have born as a black color or he must be a Dravidian bcos their color is black, i think after aryans invasion the Brahmanism there were racial discrimination, first with color the blacks would have been looked inferior , till now in our culture this still prevails. everybody wants to be white bcos we have in our blood that white is superior color, so how can a hero be protrayed whos color seems to be 'black'. so they made it blue color and there is no blue color in his body he should have been black which were looked inferior.
Thats y ravana and many asurans (so called devils) were protrayed in black color which symbols evil which is entirely biased which was done due to brahmanism. even Ravana who said to be evil, it is said that even his finger nails dint touch sita. it was portrayed as white as good and black as evil, so how can a hero be in black color. its al mere color, it was portrayed god as white and devils as black which is mere foolishness. There is no white or black, humans should be rated with their hearts not on their color. we have brothers who are black we have brothers who are white and all r equal and its only in our eyes we c black as evil and not in real. i would conclude
its mere racialism that he should have been portrayed in blue instead of black and i am not talking about the present situated where al r equal and there i hope we should change our view by seeing people til now in our society if somebody is white we say he/she beauty. the view should change. not only in india this view is every wer in our world. so lets be united in diversity.