I think shedding light on things people take too seriously has a positive effect.
Daniel Tosh has a bit about childhood cancer. I lost a daughter to childhood cancer. I don't find his bit to be thoughtless and irresponsible, and I don't take exception to it. I'm sure he put a good bit of thought into it. And I understand he's a comic whose job is to make people laugh. If I take exception to the bit, that's on me, not him, and I'm responsible for the suffering that results from taking exception to it.
What I think affects society in a negative way is when people see the negative is something that was intended to be positive and brings that negativity to the forefront.
I have edited my post to add a couple of points I find relevant.
In a lot of cases, I disagree that it's only on the receiver of the message if they get offended by it, although I agree that this is sometimes the case. If I say something incendiary on purpose, I should know what kind of effect it will have on different types of people. I can't just publish unflattering cartoons of Muhammad or make fun of someone's loss of a loved one to a horrible disease and then say it's only on them if they get offended; I know exactly what I'm doing if I choose to do such things.
I haven't seen Daniel Tosh's segment, so I can't comment on his intentions or message. However, what I can say is that context matters as well: making jokes involving a potentially traumatic subject doesn't have to include minimizing its seriousness. Chappelle, however, does this multiple times, and he even makes it a point to downplay certain allegations of sexual assault.
Additionally, as I said in my previous post, trauma responses significantly vary among different people. What may be harmful to someone may be perfectly fine to another, and vice versa. I think people with public platforms and large audiences should keep this in mind instead of entirely dismissing a portion of disapproving reactions as "too sensitive" or "easily offended" without taking into account the complexity of responses to trauma and certain subjects.