In normal, you lose 0% of experience if you die I believe. And that's where folks don't really GAF. In cruel, it is a little bit more severe I believe.
I'm not shitting on softcore, because I think it is way more fun than hardcore leagues. I'm just pointing out a little bit of the differences between the two. In hardcore, people are a bit more serious about their builds (which takes away from the fun).
In hardcore, you re-roll all the time which can be quite time consuming. Surprisingly, its still a lot of fun to re-roll. The worst is when you get to merciless and realize that the build simply doesn't cut it. I've re-rolled quite a few times already, and died to some straight bull shit.