Its not about feeling EXTREME remorse, or crying just because its Mikael/opeth related, that would be absurd [unless you are a close friend or something] but if you are informed of a death, it is only nice to let that person know that you're sorry, even if its only words, it would sure mean a lot more to them than it does to you. And i dont recall you ever talking about your grandmother or friend of yours, so you can't expect people to feel sorry for it.