It suppose to help the steering feel better by helping control the rebound created by larger tyres.
Is it worth it? I dunno, in theory it makes sense and of course If it looks good, It must be good, Right?
I know that they make a difference with 4B's that don't have power steering and are a standard item, but I don't think it would make a huge difference on a vitara.
I have thought about getting one, but like you I don't think it'll be necessary.