I'm generally wary of vocals for the reasons stated above - plus there's always the possibility of unintended humor/mismatch to what's actually happening during gameplay. (Cinematics don't have that issue.) Gibberish lyrics work as long as they aren't overwhelming everything else; the 'barbarian chorus' during some dragon battles in Skyrim comes to mind.
I may be in a minority here, but I also feel that if Larian is going to try a new musical style then this is probably the time to do it. Kirill had a signature style and it's probably better for any new composer to put their own stamp on things rather than trying to imitate his.
