Like ラク that supposedly means "at ease" (correct me if i'm wrong, i just learned this), why insted of writing it in Hiragana or Kanji they write it in Katakana? This is not the first instance I've seen this happening as well, can someone explain the reason why?
Aside from loanwords, Katakana is good for onomatopoeia, strange plants and animals or just for emphasis. Without knowing the context of where you saw it, I'd assume that the writer wanted to emphasize how relaxing something is. Just like italics in English, usage is not restricted to foreign words