I hike alone a lot, not out of choice. I prefer to have company. I came into hiking from mountaineering, where your climbing partner was essential and on big expeditions, it became a group effort. I think hikers, in general, do not have training in what we used to call "expedition behavoir" - the numerous social skills and "rules" that make groups function smoothly and remain friendly, rewarding and cohesive. My experience is that you have to have a defined leader (at least define who is the leader for the day and maybe trade off) and when you are not the leader you have to be a good follower. I personally enjoy taking a break from being the one who has to make all the decisions. A major factor is choosing your group or partner. This should be done very carefully and you should have talked and agreed on goals, rules, who carries what, and how much "togetherness" you want. You could hike together and then camp out of sight of each other if you like that kind of privacy - or camp together and hike separately. With others, there always is a benifit/cost ratio. I personally find that with the right partner, the benefits outweigh the costs.

As for danger, I think we fool ourselves if we are convinced that hiking alone is totally safe. It is just a matter of how much risk you wish to take and if that risk outweighs the problems that you think a partner would add. I honestly do not see how a competent partner would be more risk than being alone. For all you know, when things go wrong, you could be the one needing the help. I hike alone - long trips, too. But recognize the risk I am taking. It really makes me a bit edgy. In my perfect world, I would always have a partner!