There could be exceptions like making a game that was specifically designed to be about characters expanding their horizons to include fringe fetishes but that should be clear from day 1 if that's what you're doing.
I agree, devs have to be clear about what they're providing. My game was upfront about the plan to introduce a load of kinks in the future as the MC's sexual awakening progressed - and that there would be optional gay and futa content ahead... Much better to put some people off at the start than disappoint loyal fans/patrons later. For those games that haven't, it would prob be better to oll before adding something controversial, or to complete the game and then go back to add in fetishes for those who choose to play (lol - the "NTR Cut" or something).
However, players are always going to be reliant on the dev's inspiration and creative vision - and shouldn't try to overly constrain that because it doesn't match theirs. Players might enjoy a formula - but they don't want to get bored, either, and devs do need to change things up and keep things fresh, progress the story and the character development, and add in new features that not everyone might want. e.g. did everyone want Summertime Saga to use valuable update time to add a fishing minigame? No
but it went down pretty well overall. Equally, players might have got tired of all those blowjobs and want the MC to start getting some pussy - and the dev should at least consider it unless is goes against the reasons they're making the game.
Don't get lazy. If you think you are going to try and make a go of creating porn games then treat it like a small business and put in the 100hr weeks to get it right. If you are just part time because you're doing it for fun then be sure to set work time goal per week or else you will never get your end goal finished and you lose out on your fun.
You're 100% on the time devs need to put in to get a project off the ground - I think more wannabe devs need to realise this and account for it before their first release.