I think you are very harsh on your assessment of Elliott Frear.
People have very short memories that last season he came in to a side absolutely devoid of creativity and upon coming to the starting eleven against St. Johnstone in March, he started the final ten games, in which we scored 12 goals - he scored or assisted 7 of them. That includes setting up Moult's winner against Accies, and playing a part in all three goals in the game which ultimately kept us up against Killie. Say what you want about Moult, I'm also fairly certain we'd have struggled to stay up without Elliott Frear last season.
After starting this season, an injury at an awkward time saw Campbell emerge, Cadden put back out to the wing and Tait switched flanks and its been difficult for him to make his way back in. He was the best player on the park against Partick in December, but then picked up another injury which deprived him of a run in the side when others ahead of him were missing. It's taken until the last three games for him to start three in a row in the league all season.
His final ball isn't always amazing, but it does seem to me that he manages to get us in a lot more crossing positions than we do when he's not on the pitch. Has he had a frustrating season where we'd have perhaps liked more output from him? Yes. Is he "of no use whatsoever"? Most definitely not.