I wanted the Shaolin Monks to be a really good city defense unit (compared to the Guard, they have +3 Strength, and have free promotions, but they're limited to being built in the Shaolin Temple city) that could heal a little. The Shaolin Monks upgrade to City Guard. I was intending them to be part of the Town Watchmen-Guard-City Guard line.
I feel that once gunpowder units become available, martial arts start to fall by the wayside. I think it's kind of odd that the Training Dojo/Master's Dojo don't go obsolete until Homo Superior in the Transhuman Era, even though their benefit only applies to Melee and Recon units, and only the Recon units get the bonus once Arquebusiers/Musketmen come on the scene.
I noticed in v19 the Medic promotion line is available again to most military units -- is that intended or did something get broken? The Shaolin Monks have Medic I so they can heal a little, and when I first thought up the idea, most military units couldn't get any Medic promotions. The Monks would NOT be able to upgrade to Medic II or III since Herbal Cures (I thought) would be required to actually promote a unit to Medic without the promotion as a bonus (either assigned in the unit code or from something like Red Cross).