To know the traditional form is to know the Chinese culture, philosophy and character of the cutlure. To love, 愛, is a hand taking the heart from a friend. In simplified form the heart is missing. I don't consider someone who is a friend without the feelings from the heart. Merely an aquaintance in my dictionary. Actually the traditional form is very easy once you start breaking up the character into its radicals. Another example, 學 to learn, is another example, two hands pouring knowledge represented by the 2 'x's into a child. Of course there are also good examples in which the simplified forms are better than traditional ones. 麤 containing 3 deer grouped together... is now 粗 or 纔 is now 才 and 獻 is 献.

我看日语的时候就是啊.日语里的汉字都是繁体，会认不会写

你上的是台湾的大学？只有他们用繁体字啊，大陆日常生活中很少有人用繁体字，除了一些搞研究的人。