a few reasons why a person would cast a love spell, but the main reason is the person sees it's justified. while there are those who are older who fall for someone and decide to cast a spell, on this site, it's mostly teens, at that age hormones are all over the place so it's hard to think with a level head. a person might stop and go 'well, i'm forcing them to like me, but once we're together, we'll be happy, so it's for the greater good.'
people always say love is the greatest thing in the world, and when you're younger, you get a crush, and think it's love. plus talking to that person is a scary thought, so wouldn't it be easier if that person walked up to you and confessed their undying love just like in a movie, book, or your fantasies? enter love spells, thanks in part to the entertainment industry, many people think they just wave a wand, or drink a potion, and the person will fall into their lap.
most people need to think before they do, as well as learn about magick. sadly, most people want to get from step 1 to step 10 as quick as possible now a days, even if it means cutting out steps 2-9 to get their. the reason why there are so many is the same reason why there's a lot of comic book adaptations now, it's most requested, and gets the most views. we could sit here and talk about why love spells are morally wrong and why people shouldn't do them, but it won't really matter. one or two people might take it to heart, but the majority will skip over the however many paragraphs we spoke about why it's wrong, and ask anyway because 'it feels right.'
final point i would like to add, love spells are morally wrong depending on the person. you could take almost any spell and put the opposite spin on it, so the individual has to come to their own conclusion if love spells are right or wrong. forcing someone to do something is wrong, but some people see curses as justified if it's in defense, or retaliation. everyone's different.