First off, if TR wants to continually bang a drum on a subject he is passionate about, good for him. If you disagree with him then say so but don’t make it personal. You WZ, have used this board to talk about weight loss and personal problems and have received nothing but positive support. I’m disappointed you felt it was acceptable to make personal attacks on TR just because you don’t agree with him. One thing I learned from Elwood whose views were often the polar opposite of my own, was just because someone has a different point of view does not mean they (or you) are wrong.
Second, just because you live in an urban environment does not mean you have no access to dirt. The entire west coast is extremely urban but with amazing off road areas to ride. I have lived in Atlanta (9th largest city in America) and I know I could have found somewhere to ride offroad. I’ve also lived in NJ and even there I’m pretty sure there are places to be found. And no truck/trailer is required if you get a 250 dual sport. They are plenty capable of getting you to the offroad areas all by themselves.
But back on topic, why do more people not learn on dirt? I think it comes down to whatever reason prompted you to buy a bike to begin with. Whether you want look like Valentino Rossi or an extra from Wild Hogs, that desire does not mesh well with riding around a muddy field. I have no doubt the skills are transferable but why would you want to delay getting what you want? When you first started driving a car did you first take up karting? Learn basic skills then before moving onto a racetrack to learn to drive at speed before venturing out into traffic? Hell no, you just jumped in with some awful advice from your father and learned as you went. Why should people do any different with bikes?
So unless you were one of those extremely lucky 10 year old boys who had the opportunity to ride dirt bikes when young, most folks are going to learn on the street as that is where they plan on riding.