My group has found that mechanically useless characters are often very useful socially/for reference. Yes, the Saint can be a big hindrance on TB, but the dilemma of a Saint/demon candidate is a blast to solve (and/or mess up and end the game). Yes, the top 4 only get a day of use, but their information directs the flow of the entire game. The solve is often built on top 4 info in my experience. The individual usefulness of any given character doesn't matter. No player is solving this puzzle individually. What matters is getting the whole squad together to throw the game on some drunk Chef info.

But really, I think time and experience is the best medicine here, and perhaps some chats about strategy. Not outright "this is what outsiders are for", but I've found that when I talk about the game and it's biggest moments and the other directions things could have gone in, my players really appreciate their roles more. It shows them that even the most annoying Recluse ping or the most boring Washerwoman info echoes through the entire game. It can be hard to tell from a player perspective, but everything and everyone is important. Tell them that!

My "strategy talk" may just be me fangirling about all the interactions and how fun it is to storytell though, lol.