No original story or ls1 let's try this then
100% behind this. But I’d have the Marrionette as a Fractal too. It was a past event that shaped Tyria but we defeated it and it remains an inactive wreckage in Lornar’s Pass, with no one controlling it.
5 lanes 5 people.
Scarlet’s playhouse can easily become a fractal too.
For me, I wouldn’t like to some of the most epic fights in the game to be trivialized by including them in a fractal. The battle for LA and the marionette fight were great because they were map-wide (plus, the marionette fight lives on in Silverwastes: the final battle is that fight, improved to be less dependent on small groups).
However, the pre-marionette fights could be “fractalized” by including a random 3 of the 5 fights that led up to the final confrontation, each becoming progressively more difficult. I’d be okay with any of the previously-instanced fights being added to the fractal rotation.
However, after all this time, I doubt adding any of the above is any easier for ANet than starting from scratch and so I’d just as soon as they work on creating great (or at least good) new fights, rather than relying on nostalgia to fuel their ideas. Besides, 4 of the existing fights are already from season 1 (molten boss & molten not-boss, aether spin-cycle, and Mai Trin.