From what I've seen in the past, the devs often base their decision on what the mavs want or don't want, lol.
It's a coin on his side, I think. Because Prince Rennyn is so expensive, only the big investors can afford the card. If they make him less strong, these investors/top players lose a bit of their advantage over other players.
I'm curious whether this will start the discussion again, and even more curious about the outcome. :0)
Personally I think it would be a good idea to rebalance the game regularly. Last week I saw someone mention that the new Death healer is OP too.
If you bring so mant new cards into the game in such a short time, I think you can't go without rebalancing.