It's very rare that it is actually a well made mini game that actually contributes to the story. Most are there to frustrate you and prolong the game beyond it's natural course.
Sometimes its fun and sometimes i hate it. In Lewd Games i like the Minigames from the Game "Being a Dik". When its easy to play and you have a benefit from the minigame why not.
I think minigames can be fun, except for the ones that so sweaty, you are required to log in hours on an aim trainer to click patterns in order to time a minigame.
Problem with a lot of games that have minigames. They are not fun and dont reward the effort.
They are clunky, buggy, glitchy, grindy.. all of the above and more. And lets be honest here, it takes an experienced team to make a good game and to make minigames inside these games appealing.
Fast forward to porn games, minigames in those are mostly bad/clunky copies from existing ones. The lockpicking from skyrim, some weird guitar hero qte, some memory clone, some "find the difference" games etc... if they are not fun and not rewarding. Dont put them into your games.
If you need to do a non skippable mini game to raise an attribute in some sandbox (another "worst gamedesign" offender) over and over again, with little to no variation, you havent playtested your own game. Go play your own game without cheats.
if you THINK you NEED mini games in your game, your game probably sucks or you only have a handful of porn scenes aka not enough content in your game and you are trying to extent the game time. Dont.
A good minigame should be fun, quick, rewarding and satisfying. A nice little fishing or cooking minigame. A nice little naughty quiz with instant rewards but a max of 3 to 4 question OVERALL.
Also, dont put a timer in a game where you most likely have one hand on your cock the whole time.