Why is it that in some desktops such as icewn, jwm and possibly others it is
near impossible for a newbie to change the clock format on the panel and
I hate that.
I have no idea why you hate editing text files
The "Desktops" you are referring to here, are only window managers. They are not ment to have a full Desktop clicky clickity experience. By having just a configuration file that has all the settings in it you remove the need for 100 setting dialogs / wizards. This keeps the WM lightweight.
Is it not possible for distro developers offering icewm or jwm desktops to make
the clock format setting user friendly?
Sure, you could have a program that parses the configuration file. But where'd you put it? In the menu somewhere? The most logical way of changing the clock settings from a users point of view, would be an option offered when rightclicking the clock. This would probably mean changing the sourcecode of the offending WM.