for Geralt, them wanting to kill her (not take her, but kill her!!!), so why would he really care about their reasons? Would you try to find out whats behind the notion of a killer, who wants to kill your daughter? (plus, Geralt knows... one stupid prophecy about a child of elder blood kid wiping Aen Elle and becoming ruler of worlds) i would definitely not... that guy would be good as dead.
Again, the problem is not that we need Eredin to explain his motivations. We know why he does what he does but that isn´t the point. The point is that the game fails to present him as a serious threat. We are supposed to fear him and we are supposed to hate him but the game does a poor job of conveying these feelings because he ends up being a totally unthreatening chump. You meet him, he says some "yo momma sux Geralt" shlock and then you EASILY kill him.
This is it? This is the big bad guy the people are terrified of? This is the guy Geralt sees in his nightmares? This is the guy Ciri has been running from for years? Why didn´t she just turn around and cut off his fucking head if he was such a wimp the whole time. Ciri and Geralt are chopping up the members of the Wild Hunt like they´re nothing, and then Geralt finally gets a confrontation with his archnemesis and he doesn´t even get grazed. Why would we ever have been worried about Eredin in the first place when he´s a total all talk no walk chump character.
This is my point, we know Eredin´s motivations, we don´t need him to give some cliche supervillain speech to Geralt about why his actions are justified. But Eredin needs to have SOME interaction with SOMETHING in the story to support the image the game paints of him as being some sort of super tough scary guy. Because otherwise WHAT WAS CIRI EVEN RUNNING AWAY FROM? If Eredin is a wimp, the whole chase aspect of the story is nonsensical.