The thankful/grateful react is a very good reaction option and could open up the idea of Facebook reactions becoming a whole slew of individualized reactions to personalize and truly convey the way someone feels about a post or comment. The "like" wasn't enough, so Facebook added love, haha, sad, angry, and wow reacts. But these still aren't enough. More reactions would lead to more people expressing the way they truly feel and would transform Facebook into a better, more expressive social media platform.