Depends on which feature and which goals.

A mechanism to "like" a post? I don't see it as useful. I see it as a social media tool.

A mechanism to rank a post (e.g., as 'helpful')? I see it as a foundation for a subsequent feature to allow filtered views of long threads so that only high-rated posts are visible. Combined, this can be a real leap forward in FT usability with large threads that contain useful information scattered among thousands of discussion posts.