"At the risk of sounding like a broken record, you guys really should read Phil Sabin's "Lost Battles"."
I have read it. Lost Battles is a great book. I like the schematic system he created, more than my colleagues.
Other people were never into it. Therefore is is a great simulation that people didn't want to play- because of various needs of gameplay.
I can only say that Lost battles is not a "wargaming tabletop" game as stated in the question (although I have seen versions played with miniatures).
No doubt that Sabin's views on simulating asymmetry is better than any tabletop game does- mostly because it is zone based and as stated schematic.
Zone based or grid based tabletop games are a matter of a person's cup of tea. "To The Strongest: is another system that has merits for some of these situations, it too is grid based and therefore more difficult to convince others into playing.
Ultimately few of the Lost Battles scenarios had replayability or competitive play in mind, which is the go-to conditional for ancients in most cases.
As for Carrhae-
"he explains how the Roman player is pretty much forced by circumstances to follow the historical battle plan"
I must admit that I will go back and re-read that section. In recent readings of other works I still cannot fathom what the "Roman plan" was. The Romans failed because they refused to understand they were marching into a totally unforseen tactical ambush, that worked perfectly.
So the only plan would have been to uncover the enemy's goals and stratagems and counter them before offering their army for destruction by a smaller force.
I agree that tactically Crassus had more options than what apparently transpired, but his mistakes were made based on assumptions that gamer's already know in hindsight. Such as:
1: The Parthians have a large force of cataphracts, which were revealed only when the battle commenced.
2: The horse archer deluge of arrows would not abate when they ran out of arrows- because the Parthian general created a unique frontlines resupply method.
3: The Roman allied cavalry (other than the Gauls) were inferior, most had already run away.
4: The Roman mercenary skirmishers were inferior or unwilling or incapable or just eliminated.
All those things IMO make this a tough "tabletop" battle, including the space/time distance. The main army in square takes a pounding. then there is a break out by Publius Scipio that would take his force off table- to another battle where his forces are overwhelmed. Neither action helps the other except to allow the main force to retreat eventually. Timeframe is another, the attrition battle is only workable over a lot of game turns.
The other issue is that the Roman army wasn't really destroyed until they retreated, left behind thousands of wounded. Once the Romans fled and discipline broke down then that's when the army was mostly slaughtered, days later.
So really it goes back to what is victory for the Romans.
Just standing there is not a win- because that is how it played out in reality. Destroying the Parthian forces is practically impossible unless the Parthians simply offer themselves for destruction in close combat.
But I will re-read Dr. Sabin's remarks once again, so thanks for the reminder.