I would agree that the risk of not having enough unique fabricators to ensure that there are plenty with ship types you don't already have is worth the benefit of having ship complexity settings always obeyed. Also, do fabricators obey ship type disabling (like no Mk. V spire maws when swallowers are disabled)?
Also, is this in any way tied to AI Mk. V unlocks sometimes being able to bypass ship type disabling (like Mk. V powerslavers for the AI when swallowers are disabled, as one person reported)?