Maybe our use-cases vary, the forum I am creating is for an expats living and working in a certain country just like https://www.englishforum.ch/forum.php
but for a different country. And there, the like/dislike and reputation system is very widely used. If you are making a forum for basic Q&A about your software like Nginx, you don't need that level of engagement, for a social activity such as sharing stories, opinions, it's highly important, which is why most of the other forums have it. If people didn't fancy reputations or some type of rewards, sites like stackoverflow wouldn't be as good or crowded as they are now.
So to wrap it up, reputation are very important but that depends on what you want to do with your forum.