Perhaps it's a way for the author to explore different themes and challenge conventional character archetypes. The decision for her to be a villainess might be to create tension and drama in the manga's narrative.
One of the main themes is redemption. The villainess gets a second chance and tries to right her past wrongs. Another theme could be love, as she might develop new relationships different from her first life. And there's also the theme of power struggle within the story's setting.
In my opinion, the villainess is the most interesting character. She has so much depth, with her complex past and her attempts to rewrite her story. Then there are the antagonists from her first life who still pose threats in her second life. Their motives and actions add a lot of intrigue to the story. And don't forget any side characters who might help or hinder the villainess on her new path.
First, you need to come up with a unique and interesting character design for the villainess. Make her have complex motivations and personality traits. Also, think of a captivating plot that keeps readers engaged.
Well, 'A Villainess for the Tyrant' manga is appealing because it offers a fresh take on the typical romance tropes. The world-building is also quite impressive and draws you in.