"一个人只拥有此生此世是不够的,他还应该拥有诗意的世界" 立意不错，但文法不通。

此生此世 and 诗意的世界 are 2 different concepts, it doesn't make sense to compare the them together. Everyone has a life time, whether it turns into a dream world or a barren land, it is up to each individual to decide. Clearly a poetic world is more desirable than harsh desert.

Maybe he has forgotten how to write in Chinese properly, like me.