At what point did I say I don't understand why people use this trope for drama?
I said I don't understand why it's so common for the trope to go from, "This random guy decided to shoot his shot with a pretty girl he saw in public," to "This guy is publicly assaulting the woman for saying no."
I just said: escalating lack of boundaries. It is common for the trope to involve random (frequently nameless) strangers being inappropriately insistent on having a main character go somewhere with them to the point of using physical contact and casual restraint to do so because fiction is not reality and people refusing to take no for an answer is a source of drama that still doesn't escalate the story to an entirely different genre.
It's manga. Grabbing someone by the arm may be assault by the legal definition, but as a dramatic action in the same sort of nonspecific public space as any comic where the characters in the panel are the only thing we ever see it barely rates as unusual for an unfortunate turn of events, especially in this genre and general situation.
It's commonly used as a dramatic beat because of the same storytelling trends that have delinquents everywhere in school manga more generally and Mangadex comments complaining about "herbivore" protagonists in ecchi manga more specifically: a grabby rando who very directly implies he's not going to take no for an answer to his proposition is a useful thing to bounce off a protagonist who is respectful of women's boundaries to a normal degree as an opportunity to rescue a love interest without the larger-scale situations that someone could be rescued from a la superhero fiction or fantasy.
You said the trope was a bit played out and then said you don't understand why it's so common for Japanese mangakas to use it in a way that it was barely being used as you described in this mildly-sanitized version of a series where TS succubus powers and other hentai tropes are in play. It's played out because it's used a lot and it's used a lot because it's an easy source of drama, and nanpa being banned because of fear of abduction and rape is a very clear explanation for why "random guys hitting on pretty girls will drag them somewhere without their consent" is in the manga-reading public's consciousness for the demographic that reads stories that use it as a trope.