The recommended dietary intake of vitamin D and others are iffy, are they not?

Most places online say people recommend about 400 iu of vitamin D. Not a lot of vitamins have like almost 700 iu plus if your eating salmon, eggs and diary and eating healthy your getting a ton more than 400iu. Also there is new somewhat hidden research that suggests that vitamin D is one of the most important vitamins in supporting your immune system. I mean it is like the only self generated vitamin (sun). What is your take on this? I am sure getting a lot more than the *daily* recommended and i am not suffering from the harmful side effects of supposedly toxicity...