Cavalry units are amazing and funny, fast and powerful.
Heroes in history always fought riding their horse, and when they choosed to fight as infantry this was recorded (example: King Henry V in Azincourt battleground, when he fought side by side with his few and tired soldiers without keeping his chance to flee. One of the most extraordinary victories in the past).
Having heroes in cavalry units should be permitted then.
Another good reason is the actual cp calculation. Having an hero on every unit raise the amount of cp in insane and suicides. So, this lead to the decision to not pick a cav for a heavy, for this lower the total cp gained. Another reason to leave ironforts to the rust.
Also, having cavalry with heroes could counter the overpower of the ranged in the current system, having a bit tougher unit running toward the archers could be a challenge (at least they have the chance to touch them...).
The cavalry remains vulnerable to fire, and heroes will die fast, so i believe this won t alter the game too much.
The reasons to not allow heroes in cavalry units surely were good, but since that time the game changed a lot and many times, so i guess it is time to reconsider this restriction.
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