That is the question I have been pondering over the last couple of days. Does Via Astrum need flaws for the characters? And if so, what benefits do they derive from these flaws?
I have come up with a short list of flaws that I would include. But by taking a flaw, what positive would balance it out? In Champions and GURPS, disadvantages give you extra CP to build your character with. VA does not use CP. There are the Variance points which could possibly be an answer. But then, take a lot of flaws and you have super stats. So the number of flaws should be limited. It also gives a Flaw a de facto xp value of 10-20 xp, depending on what the Variance raises.
If Variance points are not handed out for flaws, what about Talents? That would give a Flaw an xp value of 10xp. But again, the number of Flaws would need to be limited.
Or should Flaws be some mandatory quirks? Not on the level of full fledged flaws/disadvantages, but personality quirks that drive roleplaying? In that case, they would not provide any mechanical positive benefit. They would merely help you define your character for roleplaying. This is my least favorite choice. If the player does not want to give their character any quirks or roleplaying tags, the game system should not force that on them.
And then there is that tiny little thought at the back of my head. Am I adding flaws to just be adding new things? A lot of roleplaying games do not have flaws as a mechanic. They get by just fine without them. If Via Astrum were a point based system, then flaws and disadvantages would be added without hesitation.