There weren't a lot of apps prior to jtagging, because there was less interest in it (why dev for other devs?). Once we (the public) had a way to run unsigned code, writing a program is suddenly appealing, because more than a handful of people will see your work (and most of them won't be other devs). Basically, it'd be like if the only 360s in the world were the rare "launch team" models, and MS only made games for them.
As for why devkits deserve fp attention, remember this is a xbox site. Since it's xbox-scene, if you were to rule something out, it should non-xbox and non-scene stuff. The front page is generally nice and clean here, and quite easy to check time to time for news on new homebrew and hacking goodness (weras other sites may have a lot more stuff like new retail games, etc and news can get lost).