The jokes are easy to imagine but I really wonder how people can joke at a decent person's death. He was an okay actor, driving with a friend (some reports say he was the driver, others not) and died tragically. You may have no care for what people say about you after you pass but what about a joke told of your friend's/father's/mother's/teacher's/favorite waitress' death?
Joking about someones death and feeling sad over that death aren't mutually exclusive. Gallows humor is a thing. These are celebrities and as they are hounded in life so too are they in death. To compare them to random people is both unfair and missing the point. I go again to Steve Irwin who has been the butt of every joke from:
to
Insensitive? More like irrelevant because we didn't
know Steve Irwin the same way we didn't know Paul Walker. We knew a character. We knew their livelihoods. The crocodile hunter lives on, he's probably gained more fans since dying (that skyrim meme is some five years after Irwins death) and this fame will propel people to watch all his crazy antics (money for the family) but more importantly his message about loving animals and protecting nature.
tl;dr - trolls gonna troll, try to see positive in a persons life because they're dead and nothing is going to change that.