It's a complex interplay among factors: enjoyment, responsibility, impact on self and others, "justifiability" of the activity. There isn't a clear cut answer, but I would say that it is most definitely true that, at some point, increased safety leads to decreased enjoyment.
Years ago, I made my first trip to Europe, and climbed up a memorial in central Germany. There's a catwalk around the top of the monument, and you can go out on it and lean on a simple railing and get a splendid view of the countryside. What struck me was that there wasn't any netting or chain-link to keep you from climbing up on the railing. There were no signs warning about the dangers of getting too close to the edge. We were being treated as adults who were capable of making rational decisions about what would be safe behavior and what wouldn't be. But, of course, most European countries do not have the litigation climate that the US has.
But the problem with that approach (which I like, as you can tell) is that, as a species, the human race (in my opinion) tends to be incredibly stupid with respect to assessing risk and adjusting behavior accordingly. I work in an ER, so I know this. In addition, when we DO try to assess risk and behave responsibly, we're often working off flawed data or assumptions. For example, many times, people on this board have said that your greatest risk of death related to diving is the drive to and from the dive site. This is quite probably true. But we get focused on the risks involved with the diving, in part because we're enured to the risks of driving, and in part because a lot of them involve matters over which we have no control whatsoever (eg. the guy who just left the bar after several hours of serious drinking).
I'm no better at this than anybody else. I ride my horse without a helmet a lot of the time. I don't do it on trails or in venues which are new to her, and I don't ride strange horses without a helmet (except in Botswana, where I rode for three weeks without one, on hard ground and where animals could have jumped up and spooked the horses at any time . . . go figure). But I practice emergency procedures related to diving on a very regular basis, dive double tanks for deeper dives, dive Nitrox . . . I work hard to mitigate risk where it's probably fairly low to begin with, and ignore higher risks in other places.
I think most of us are like that.