I choose "be gentle" in the moment because in that setting, I think it's sweet, and an intimate connection. That doesn't mean I think my PC would cover to Astarion in every kiss going forward by any means.
I *do not* want to RP ab*se or DV. Nor do many of the people who chose "be gentle". And I would have to meta game to know which one would I would be getting. An always on my toes about it. That's not fun, nor in the spirit of Rooney's "evil but enjoyable enough to bring to the table."
hence why it makes sense to just have two dialogue options. of course, if you choose "be gentle" once doesnt mean anything for the next time. but his kisses arent gentle, he bites and pushes, in whatever way you interpret it, it isnt gentle or soft in and of itself. this is why people play AA and not UA. because of this treatment. it can be interpreted in different ways. this is no more meta-gaming than choosing not to sleep with him or farming his approval. if you want smiling tav they wouldnt ask for gentle kisses, because they are not gentle to begin with.