At least on Google Translate, "мне всё мало" is "I'm not enough", which is something I cannot understand. Judging from other uses of the dative case and the word мне, I understand why other constructions such as "Мне не хватает", would work.
Why "мне всё мало" is "I'm not enough" [...]?
You're right, this translation doesn't make any sense.
Depending on the context and stress position (marked bold below), it could mean:
"Мне всё мало" = "I can't get enough" with a strong connotation of uncontrolled greed. It implies that the person has already gotten more than enough of something (which should be clear from the context), but still can't stop and wants more.
"Мне всё мало" = "Everything is too small for me" — in the context of clothing. For example, imagine someone who's recently gained a lot of weight, scanning their wardrobe with deep sadness.