It is true that, strictly, the color of the wine has no bearing on the efficacy of the sacrament, but would it not nevertheless be beneficial to have it look like blood, if only for the edification of the faithful?
No. Because if the Church or a priest were to insist that the wine be a similar colour to blood, there is the danger that, in the minds of the faithful, it will come to be seen as something that is a mere representation - (it only has to resemble blood if it merely represents blood. Otherwise, it doesn't matter what it looks like). Granted, with proper catechesis, this shouldn't happen, but it
is a very real danger. However, if the faithful see that it is treated and revered as the Blood of Christ, regardless of what it looks like, then it becomes clear to them that it isn't merely a bit of symbolism, (which is the protestant view), but rather it is the Sacramental reality that the Church teaches that it is - the Body and Blood of Christ under the physical appearances of bread and wine.
If the wine must somehow resemble blood, then the logical conclusion to that argument is that the bread must somehow resemble human flesh, which brings me back to the original point that because it isn't a mere piece of symbolism, it doesn't have to look like what it is. (and for that I'm very grateful

)
Actually, if you examine both Latin and Byzantine commentaries on the liturgy, it is indeed a sort of play, with each part symbolizing a part of the life of Christ. It wasn't originally so, but in the middle ages it was interpreted that way, and various accretions and modifications to the liturgy have been predicated on that assumption.
I have come acros such ideas, partly in
The Stripping of the Altars, and although I agree that yes, some accretions are helpful in showing what part of the Mass is about, the Mass itself is not a play. Parts of it, or indeed the whole thing, may be allegorised, but that doesn't mean that the heart of it, the re-presentation (as opposed to representation), the anamnesis, the making truly present of the Sacrifice of Calvary and the entire saving work of God, is reduced to a symbolic meal where we drink red fluid and think of Jesus's blood. Therefore analogy of the play
may be helpful, but that doesn't mean that the Mass itself actually
is a play. Do you see what I mean?
Happy Sunday, BTW!
In Christ,
M