Who's to say that? The devs of course and they're indeed saying it I just don't feel it's entirely true, I'm sure they're making the best of it but clearly they picked a character that has a following right now for the reasons they've stated and I just don't think Geralt will transalte into what people like about SoulCalibur neither will SoulCalibur translate to what people like about Witcher...
If J.K Rowling decides she wants to put aliens in Harry Potter and that's where she thinks her books are headed then I see no reason why she can't and you know what, people would buy it and even enjoy it... I'm not saying I'd buy it but then I've never been into Harry Potter books. It's like I said , the only limit is what you have the ability to successfully implement. Also did you really just compare a gameplay feature the devs actually may want to implement to microtransactions...? Yeah, no.
Going on what you've said I could also easily say just because the devs decided to implement Geralt doesn't mean it's a good idea and that's what I'm indeed saying but I also recognise and respect the devs position of responsibilty in creating their game and their autonomy in doing so. It's up to the devs to make their game, not us, and it's down to them if it all goes wrong, not us. They're the ones carrying that burden so don't you think they deserve said autonomy?