While the well of sorrows was a hard and important choice in Inquisition I can kinda understand why they would make Morrigan the cannon choice in that it's probably the choice that make the only since in the story Vailguard is telling. It sucks one of the biggest choice you made in Inquisition is being picked for you but sometimes the only way to tell a full story is to canonanise one choice over another. Another thing, I feel like the only reason romance choice would be important to the story would be as a female elf the inquisitor romanced Solas, that would have massive story elements on Solas's character and I can see why that would need to be clarified before starting Vailguard