The intent for why we train is completely subjective at this point in the Parkour community. I honestly don't see how this thread going any further is going to help someone make a better decision as to why they do Parkour. Did the original french practitioners, or many of the top athletes of Parkour today use forums to figure out why they train? No, because they are content with themselves after figuring it out on their own. Certain ideas are great to discuss, but I don't think this is one of them. It's your own personal journey, and there is no reason that others should make a mark in it simply through opinion of what they think is right and wrong.
Ok, for you this discussion isn't useful. For me, it is useful. For the other people taking part in it, they think it's useful for them. The people that think it's useful (like me) can take part, the people who don't (like you) can go do something else. Everyone's happy.

The original French practitioners didn't use internet forums because there were no internet forums (there was no internet). What they did instead was to talk to each other, talk to their relatives, their friends, trying to understand what they did. You don't develop understanding of something without thinking about it, and discussion is a useful aid to thought. Discussion is not essential, perhaps, but it is useful as it forces you to put your thoughts in order.
Sorry Dave, but I have to disagree here. When I got my first ever vault, for example, I was constantly looking for higher and higher things to vault over. That's not me encountering different obstacles, that's me trying to apply my movement to things I go out to find. I look for obstacles in my training, rather than simply encountering them.
Yes, we do have to look for obstacles, but I think it's a major mistake to look for obstacles with already the intention of performing a specific movement to get past them. Doing that teaches you to use that technique in different situations, when instead you could be learning how to find the best way to get past those new obstacles. What it does is teach people to rely on certain set techniques, because they never try anything different. You get good at cat passes, but you don't get better at getting past new obstacles. I've seen many people that are very good at certain techniques, but that are simply incapable of finding a solution to a new obstacle. To me, this is useless.
I also experiment with a ton of different technique on certain obstacles in order to improve my capabilities elsewhere, which is training in an equally constructive manner as going out to find hard obstacles you can't overcome. An example of this is when I had learnt the pop vault over this wall just above head height, and instead of moving on to a harder obstacle, I went on to train on that wall for another month, until I had been able to kong vault, rather than regular vault, over the top.
Experimentation is good, it helps you learn, but there's no point conditioning yourself to use poor solutions by continually repeating a movement once you know it's not the best way for you then. Sure, in the future once you've become stronger, you will need to experiment again, because you've changed and the solution will change also, but I think it's absurd to practice ineffectiveness.
The art of getting past obstacles is in trying to make it as easy as possible for yourself, being as efficient as you can in the situation. That's the skill that enables you to do the most, because that's how to learn to function to the limit of your ability.
I see where you're going though. When you have an obstacle you can't overcome, you would obviously try and find a solution to get over, under or through it. But that's only one aspect of training for me, and probably for a lot of other people, too.
Without wishing to cause offense, we've made the point already that there are a lot of people that aren't training effectively. Lots of people spend a lot of time practicing movements on obstacles where they aren't useful solutions, but to me that's simply one indicator out of many that we have a long way to go before the practice of Parkour is properly understood.
It's worth reminding ourselves, though, that there are aspects of obstacles that aren't determined solely by it's physical qualities. The complete obstacle might involve an element of repetition, for instance, or speed, or silence, or safety, or any number of other requirements. If that sort of thing forms part of the challenge then you may well need to use a different way of moving to successfully solve the problem. However you still need to set the challenge before you find the solution to it, if you want to be good at getting past obstacles instead of simply good at cat passes.