I think it's more people either commissioned or wrote in their OCs/SIs to put in game for fun (fenco/savco games have always focused on input from the community through submissions, donations, commissions, etc), not necessarily that they paid money expressly to fuck and fuck over the player.
That looks more like a truth, chars was just 'laying' around and was inserted into the game for fun.
Granted I don't think it's a very good practice long term because I think it's very easy for writer's to run into the issue of writing solely from their OCs/SIs perspective, instead of from the player's (or considering the player's input). I think that's probably part of the issue with content that feels like the player is being ignored or are expected to find this new character hot and if you don't you get negative companion comments or corruption points or whatever.
Not only that. Such chars are interfere with the whole game/story. Sometimes (most of the times actually) its important for progression of a story to add/do/etc. some global scaled things, which concerns/impact everyone and everything. And if character are not a subject of this global scaled event it will ruing, well...everything story related. Other characters, story mood, audience satisfaction, etc.
Like, for example lets imagine some abstract text porn game, in which, hmmmmm...well, some cult summoned a daemon from the underworld, yes....oh, and lets that summoned daemon is a futa....and...and it also have some motherly related internal problems, like it want to be a mother but cant because daemons cant have ordinary children, or something.....emmm, and that cult done this for....mmm...to obtain...ehhh, well, lets say MO` POWER for cult leader to....I dont know, to become local dominant political power, like king or baron or something...literally fuck its way there, okay!? Okay!!!
Now, lets escalate things. That aforementioned daemon started to fuck/be fucked with/by everything that moves in world, in which it was summoned, and instead of full fledged, or at least half breed, daemons copulation results always would be a...some demonic trash, like...imp or something, Im not big into demonology... Now lets say that that imps are a serial rapers, because....because we have a porn game, remember!?
Now, it would be really stupid to add to game with such premise, like...ehhh.....a blonde cat girl, that that have ombre pink hair....and that also is a....pffff....a harlot of a god of love and art, and....emmm...and which also sterile, in sexual plane...ehhh...and which acts like a "oh, I didnt noticed you were there...hey, lets fuck!!"...oh, and which also know a wide range of both offensive and defensive magic...and which also, for some unknown reason, are loved by pretty much everyone...ehhhh and which also...well you get the point, generic mary sue.
That will be really both stupid decision of adding such character and character itself, right!?
Because
a) story with such character are not interesting/funny. She will successfully do anything in first try in one go. Thats nor fire, nor water nor someones work to be interesting.
b) turn story into budget circus, due to her invulnerability/plot armor. Rape daemons invasion? She easily reach the end of a such story as virgin in/of all holes. Descriptions of """""rape""""" scenes will be full of "imp dick missed her
hole_name, like a shot with 95% hit chance in new x-com"
c) make progression of a story/and pretty much everything pointless. Because of 'first try success' even dream team from gods or some kind of interdimensional horrors will fall from the mere sweep of her left hand.
d) if its a side character, not the main character, she will overshadow the main character and make him looks like a joke on a player, a really bad joke.
Good thing that was purely imaginary game and nobody done something like this, right!?
