Either there is some kind of weird Geralt fetish indeed, or it's incest fetish again.
In TW3 the devs did a lot to portrait Geralt as her father, even if not blood related. While her interactions with Vesemir and other witchers are much more rare and limited.
These days, when patreon banned blood related incest, all those countless incest-based games switched to this "legal" type of incest, without blood relation. No point in pretending they magically have nothing to do with incest now.
Some people love incest fetish and others hate it. Either way, both can't be pleased at the same time. Even if the main character will change his disguise, I bet there will be people not liking the new disguise "because it's not Geralt".