RE: ARFs versus kits
From the perspective of a relative beginner I think the difference is the intimidation factor.
I've been interested in RC flying for quite a while, but just never took the time (or had the time) to get involved. I believe that if I thought that my only way to get into the hobby was to build my trainer from a sticks and glue kit I probably would have just passed again. I'm reasonably "handy" but working with small pieces that require a lot of detail and patience is not my strongest suit, and isn't something I particularly enjoy. The availability of ARF's & RTF is what convinced me to take the leap.
I suspect that there are a lot of folks like me who gave it a try because they could go to their local hobby shop and purchase equipment that would allow them to get in the air in a reasonable amount of time, with something that is known to fly well from the git-go. The availability of ARF's and RTF's has to have had a positive impact on the number of people who try the hobby and then stay with it. It also gives those same folks a huge variety of aircraft to choose from for their 1st, 2nd, 3rd, etc aircraft. At some point down the road I'd like to fly a large scale Skylane (such as the H9 ARF). I've flown them full scale and would love to have a model. The thought of spending 6-9 months building it isn't real attractive to me at this point, because my main interest is in the flying.
I will probably build a kit or 2 down the road, if for no other reason than to develop some repair skills. And who knows......I may get as hooked on building as I am on flying.
I flew small control line planes as a kid, and knew from the start that I wanted to go glow rather than electric. I just love the sounds and smells of the glow planes.
Bob