Nothing wrong with singing just for your own pleasure. However if you're going to sing in public, whether in a formal performance or a more casual setting, then you should put a bit of work into it, in order to put in a decent performance.

The implication contained in the OP was that "proper" folksingers aren't entertainers. "Entertainment" doesn't necesarily mean cracking jokes or "giving the punters what they want", it's about giving a performance which others will want to listen to. That's what folksingers should aim to do.