I see a lot of these posts going around.
I do not suggest adding any new parts, or islands, or anything unachievable like that.
I suggest a simple change that can enhance the building and sandbox experience;
Remove fuselage and wing edit limits. If someone wants to re-shape a wing that collides with something, just let them do it. If someone wants to add a fuselage section that would collide with something, just leave the button there. These restrictions make no sense, given that the developers themselves provided the fine tune panel that will let us (with a bit more effort) achieve the desired result anyway, without having to touch the xml
EDIT: Also, maybe an option to unlock the size limit of fuselages would be great. I understand that the thought behind that limit was to prevent performance issues, but what about a popup that warns you when you try to increase the fuselage size over 10, with a nice little don't show again tickbox in the corner.