What all feckin' broke in timeless and responsive monobook, or just too skin-specific to anything to work in others? What's bad in mobile? What betweens are there?
The main issue is that gadgets plug in to the interface by manipulating the DOM directly. The DOM varies according to skin.
If there were an abstraction layer in between the gadget and the skin, it could “translate” between the gadget and the skin DOM.
We have some abstractions, such as addportletlink. Need more/better/less specific and more reliable.