According to reddit, he wanted the part but I guess Larian doesn't returning his phone calls or something? There was a nasty divorce with mutual accusations of abuse apparently, but from what I can tell, he's still getting tons of work so I don't know how much there is to that controversy. If Larian is pretending he doesn't exist that makes me think it wasn't about money, because it sounds like he was very much interested in that role-besides, he was in Siege of Dragonspear and that had a fraction of the budget BGIII has.
I suspect it was the controversy or the fact that Mercer has a large, devoted fanbase in the D&D community that could be leveraged to sell games. Possibly a combination of the two, but the likelihood of the second being a major factor really doesn't appeal to me. Despite his skill, I really am not a big fan of using celebrity fanservice to sell copies of BG. Minsc has already been leveraged way too hard by WoTC marketing, IMO. Honestly putting me off the game a bit.
