i could argue the tile expansion on city capture overlaps with Shoshone to the same degree, and that’s pretty random in its own right. Huns can capture ALL units, while Rome just gets 1 UU per city. Huns capture units at 15 hp and with 0 XP while Rome’s appear in a city, away from combat, at full hp, and get XP based on the city they appear at. Overall that makes them less plentiful than Huns’ free units, but much more survivable and useable. Huns’ converted units usually just result in sacrificial meat shields, sapping the attacks of the enemy to take them off the board permanently, with the side benefit of essentially letting you draw back your horsemen from riskier kills by 1 tile.
From my post above, I would argue it is substantially LESS random than what Rome has now. I would also suggest that by virtue of being units that can move and do actions on a map, rather than icons in a list in some tertiary city, free unique units are exactly as unique as UBs, but more “special”. Not only are there more of them to collect, so you get more unique things more often, you get to do more with them.
this change would also serve to give Rome a bit more consistency in being a conqueror too, because free military units augment your military production, while free tiles… don’t. And captured UBs could do all manner of things that Rome just doesn’t really care about or have a complimentary kit to take advantage of. Why should Rome care about a more %
GPP from a coffeehouse in some backwater captured Austrian city? He could meaningfully use a free, no-supply Hussar though. Foreign UUs just fit Rome’s existing kit more naturally.