At first, noone can force anyone to like anything. No one can like a band which he never heard,even if a friend tells or almost forces him to do so because he thinks that it is the best band and that the other one HAS to like it,that's wrong imo.
So i think Katatonia should not be anything but a band to which everyone has a different opinion,like to any other band, of course for me and certainly for many other people here too it is the best band there is or at least one of the best bands.
I think to understand music one has to be busy with the band he just discovered or likes very much,get into it,no matter which band it is.
So i would rather say that Katatonia is a band which you have to listen/watch to, to understand their music and the feelings that come with it. And like someone here once said, noone can say that he truely "understands" the music and words/content the way the band does when they wrote it. Everyone filters out something different from it,be it lyrics or feelings and that's the greatest thing about music i think. Everyone interprets music different, and since Katatonia is a band which is very intensive imo, everyone feels and thinks different about it.
So for me Katatonia is a band like no other band,which i try to feel and understand and i would never force anyone to like it,ok,sometimes it is indeed very hard
Maybe i understood the question wrong, and was too much busy with the word "should" that comes with your thread, maybe it is more meant to be an "is".
So,sorry if i misunderstood it, but hey, interesting thread