Cant compare a green to a yellow, all exotics should bevat least 280 light

But why? Why should a level 20 be the same as a level 40? Every RPG does this.

I never said a lv 20 should use it im saying all exotics should be at least 280 light and that requires lv 40

Then what reason would anyone have to use new exotics?

They're the same rarity. Thus they should be equal.

I disagree . Have you ever played Diablo 2? They have unique weapons and armour with a wide range of level requirements so that you can use fun and interesting items as you level up our character. Many RPG type games do this as it adds a "step" type system of progression. The nice thing about Diablo 2 though is that they created recipes for upgrading lower lvl uniques so your favorites didn't have to be left behind. Were they as good as the highest lvl uniques? On occasion and in the right hands, yes, but for the most part, not so much. At least though the player base had the option of upgrading them and using them then deciding for themselves if it was worth the upgrade. They could have easily implemented a system like this but instead decided to just leave it all behind.