I really like having a walkthrough available, and see no reason why any game should not have a walkthrough, either ingame or mod, that the player can choose to turn on or off so that they can play the game the way they want to.
Yes, I like using walkthroughs for games like this. The choices often depend heavily on the writer's style and not what i would have chosen. so i rather just have the right answer.
Some games can be simply impassable due to the developers' crookedness. Take, for example, Ring of Lust - in it, because of errors in the code, you can run into a softlock even with a walkthrough. In general, in sandboxes the walkthrough can be very useful, because often it is not obvious the direction of your MC's actions.
In AVN the walkthrough is not so necessary, there it is just interesting to go through different variants of the plot development.
I prefer with them, I love reading, but only in the case of adult games, I really don't want to have to keep looking to find a scene I did not get, or if there is a scene I don't want (like NTR)