I think its pretty under rated.

You're all right that it is a crutch weapon, and thats a huge reason why its so looked down upon in communities like this one. However, its still a pretty strong weapon in the hands of a good player. Its definitely a niche weapon, and usually skilled players will be better off with your standard Shotgun or Sniper or rapid fire frame fusion

But there are absolutely times where it has its uses. I have pulled it out in tense trials moments and caught my oponents off guard, it can pull of cheeky kills that lead to an easy round win like that.

IMO its quite under rated as a hot swap trials weapon in that way. If you notice a team is almost certainly going to hard lane a certain choke point to start around, you can dust off ole Jotun and just nuke em away. Jotun is easy to dodge when you know your opponent has one. If it catches you completely off guard though, even a high skilled player will be lucky to have the reaction time to doge that first jotun blast.