People have this idea of what Nyx should be instead of just learning what Nyx does and utilizing her.
The most important takeaway here is that Warframe is a fast paced game where ability spaming and aoe weapons will just allow you to delete the enemies in almost every situation. And then in some of the more directed endgame farming situations like Eidolons, abilities don't work at all.
This makes it tough for Nyx to exist because of her abilities.
But, let's not all just give negative feedback on Nyx. She has two very powerful uses.
1) range/efficiency on her 4 and being able to make an area basically unkillable. This has many good uses.
2) Efficiency/duration with 4 augment. If you couple this with Arcane Energize and some of the most powerful weapons in the game it turns Nyx into an unstoppable juggernaut. Use your operator mode to dash around for mobility and/or utilize your melee combos. Infinitely scaling melee weapons work for her. She can't be killed, she can't be cc'd, this is THE frame to take if you want to just ez mode most missions for any length of time. I have never had an easier time doing a 6 hour survival solo. (outside of Octavia, of course)