I see this game as a good platform game, not just a simple hentai game. Therefore, I think the complexity of the bosses and the plot is also important here. I love platform games, especially complex ones. So I don't think bosses should be easy.
That feeling of a long-awaited victory is lost if the boss is too easy. As they say in Russia "Без труда не выловишь и рыбку из пруда")) (Nothing can be achieved without effort).