Such a good nukige.
I don't think there is anything inherently wrong with games like Happiness Double Room.
It's just a decision made by the author, who can decide which elements it is better to focus more on (story, hentai content, or even a mix of both).
When a game is a nukige, it must be evaluated according to its genre (this applies to any product of entertainment).
A nukige is not a b-tier game, it is a game with the same dignity as others (for example the story-oriented ones), because the belonging to a specific genre doesn't automatically make a product worse than others.
When it is stated that a nukige is worse than story oriented games by default it is like saying that comedies are always worse than series that deal with sensitive topics such as drugs and prostitution. This is not always the case.