The Anime Man explains this in his video.
People get lazy to read the blurb of the novel (the short summary usually at the back of the book) to know what it's about, so a longer title will be more descriptive than titles like "Wish".
The LN industry is getting bigger, therefore everyone will eventually run out of titles to use (even movies there are ...
Why is this style of title so common? How did this trend of super long titles come about?
From what I was able to research, light novels and/or manga have long title:
Because it helps the light novel/manga stand out
Due to the competition in the industry, authors have to find ways to grab the interest of readers. One such way that has become popular is ...