It is a challenge and frustrating... but a rehashed primal is not imo "content". You have seen the Titan fight... there's nothing you miss by not completing it in HM or EX.

A relic is not content, it's a reward.

It would be one thing, if you weren't able to see the primals at all, because of high end gated content... but you see them as part of the main story. After that, they are all the same but with different abilities. That is not denying content to anyone. (..and I am a casual)