I think they’re hoping that at least some percentage of people will shift to showing their appreciation via comments or retweet more. Either way, it serves to make people more vocal about what they like and if that works, people will come to expect the comments to not be a total cesspool & also see more “positive” endorsements via retweets. It doesn’t make Twitter’s problems go away, but it does aim to shine a spotlight on people’s positive experiences on the site and in effect change the user’s perception of the positivity to negativtiy ratio. For those of us that use likes to bookmark tweets, I guess we’ll just have to use…the bookmarks feature. Of course, there’s more considerations to this - how likes may be used to game their system, taking away an outlet of positive expression that people are used to.
Self promotion disclaimer, but this is relevant to the topic here. The short video app I’ve been working on, Roobit, dispenses with likes/comments. It’s replaced with rings that glow cooler to hotter as the overall activity around a video increases, i.e. the more people collaborate & chain video responses to the original, the wider the reach & views. Rationale - since the overall popularity of a post (how hot the ring glows) is tied to both the amount of collaboration it drives & views, the hope is it will allow the community to combine their creativity & ensuing rewards. You could (very) vaguely think of this like a video version of Twitter’s “retweet with comment”, though the intention is more to combine short video stories with a Pinteresty group messaging dynamic.