I'll encapsulate the argument:
First, we'll consider, for purpose of argument, everybody to have a power role: the nominator.
Now, let's look to normal mafia...
Why do we not reveal night action targets the day before unless it's absolutely necessary?
Because any premeditation of night actions that mafia can know about
can and will be tampered with
. Don't underestimate the creativity of the scum. Also, considering the flavor of the game, don't count out the presence of scum power roles that deal with nominations. Romanus' claim already shows us that there are nominatory power roles, and I would be surprised if none of these came up scum.
So, because of the unknowns, and because of the myriad of ways the mafia could tamper with the nomation process, I feel that it's better to pursue this on an individual basis. Allowing mafia to know who to kill to narrow down the lynch board is very much a bad plan; allowing them to know it at all, in fact, is bad, because if one of their own is on the platform, they can intentionally BROADEN selections through their sabotage.
The plan of revealing nominations before they're made is disasterous. Info is info, yes, but showing the mafia our hands so that they can surgically strike the weak points is in no way a good play.