It seems that Larian wants to discourage people from romancing AA. The problem is that AA is much more fleshed out than UA. There is so much more characterization with AA and more content in general with him, especially when romanced. Romancing UA feels undercooked when compared to AA. So that is one of the things that makes AA more appealing to me... his better fleshed out romance in act 3. Also UA kind of doesn't feel like Astarion. It feels like AA is who he's been the whole time, just with more confidence, like his voice actor said. It's like UA was an afterthought. Perhaps the botched AA kisses wouldn't feel so bad if the UA romance route was fleshed out more.... but I still think AA fans should get satisfying kisses, which means not forcing unhappy expression on peoples' faces.