Just want to weigh in in support of the option of sourcing the marriage rather than manually putting the sources in both spouses' profiles. I highly value the emphasis that WikiTree places on sourcing and I spend a lot of time tracking down sources for the profiles that I create. That said, I have wrist issues that are aggravated by working at a computer, and all those copy/paste routines add up.
My ideal would be if a source could be attached to the event (the marriage), viewable from both spouse's profiles, but stored in just one place. But even if we had the option of adding a source and indicating that it should be added onto each spouse's source list, that would be an improvement from my perspective (as noted by others, this approach means that edits in one profile would not affect edits in the other profile).
All that said, it's probably worth clarifying that even if we were given the ability to source a marriage rather than add the sources to individual profiles, I wouldn't be advocating for making that a requirement. I recognize that people may have reasons for preferring to add the sources to each profile individually.