While I think Amiga needs some game making tools, if you make it too simple you run into the same problems as Shoot 'Em Up Construction Kit
(often abbreviated as SEUCK).
The best thing you could do to make a good game development kit is to make it as open-ended as possible. Make it possible to write object codes in C and link them with a standard linker such as VLink. That way the user isn't limited by what's possible in the simple editor.