While I exploit that to my fullest, I do agree, I do nothing but save my promotions for Insta-heals..
Which is not that good really, I love nothing more than Siege units that have +1 range, logistics and if they so conveniently attack rough land (I usually take barrage lvl3 to get the logistics) they take enemy armies apart.
Same goes for airplanes, two attacks in one turn? Awesome!
Instant heals are not needed if you can destroy the enemy army fast enough.