Historic also gets rebalances, meaning they don't have to worry about banning/unbanning as much. If a card's too powerful, they can just nerf it when they feel like it. For example, they could decide one day that [[Orcish Bowmasters]] should only trigger once per turn and cost 3 mana. This would pretty much only cost players the wildcards they spent on the cards, which they have historically shown they're more than happy to effectively delete from people's accounts.

I'm sure historic will see some changes over time. It has some answers to [[The One Ring]] that don't exist in modern (like [[Fragment Reality]]), but no [[Urza's Saga]] to fetch out a [[Haywire Mite]] or anything so you're left with some pretty inconsistent answers.