Sure, and I don't complain, I'm just saying that for this time period their existence isn't very realistic. And I definitely agree there was some serious effort to make them civilization-specific.
Please rest reassured I'm not dissing 0 A.D. here, I'm the first to admit it's a game and fun should take the lead.
Now for the ceterum censeo Carthaginem esse delendam: Rams are overpowered...
My strategy is to usually build groups of 10-20 rams and send them in waves into the enemy camp (I've scouted before). The enemy kills some, but can't block all. And since the AI doesn't repair (much?), the next wave finishes what the previous started... Once there are no civil centers left (easy to spot due to their influence borders), and all enemy towers have been destroyed, and all civil buildings have turned to Gaia, I just send in the cavalry and a few (10-20) spearmen to mop up the survivors. Works every time, even more easily on maps with water where you can land near your target and avoid a long journey.
In my game I've now weakened all rams by making them even slower, twice as long to repair, and by upping all fortress/tower resistances from their initial Hack:20, Pierce:35, Crush:3 to a more serious Hack:55, Pierce:55, Crush:10 *. This gives the defender more time to do something. Previously, if no ram-busting unit was already very near the attacked structure there was no time to do anything, the structure was doomed: 3-4 seconds and the mighty wall was rubble... Yes, I didn't change their attack values, because they should remain deadly against other targets (civil buildings, wooden structures, etc.).
* I would also had substantially increased the cost of towers/fortresses, but since the AI apparently loves building dense networks of towers and fortresses I'm afraid this might cause it to outspend itself, USSR-like...