I like (haha) “thank you” as it focuses more on an action than a person. Similar to your suggested feature.
And with a heart icon, that also speaks more about deeper emotions. A hand making a thumbs up speaks of a gesture you give a coworker, a team you work with to forward a group’s goal. A heart you give to a bestie or more; something more personal for individuals to share privately. This may be Facebook’s line of logic to have likes represented with a thumb-up.
Changing the heart to the thumbs up may be the only change needed to turn this behavior around. As the universe dictates that the most easiest solution is usually the most appropriate and most useful (much to my chagrin sometimes…).
This whole thing reminds me of a very specific logical fallacy.