[Why do people hate Baruuk so much?]

I think it's because Warframe lacks any form of feedback for helping your teammates that doesn't include pulling your weight with kills. 

Baruuk (and many other frames like Trinity) would feel far more helpful if we had statistics to show that you indeed helped. For example, end-of-mission results that show:

1. Healing done by you to yourself and others

2. Damage mitigated using armor/abilities/melee blocks

3. Objective-oriented goals achieved (like energy cells brought to excavators)

And so on. People could look at those statistics and think "Wow, that Trinity sure kept me healed up that game and did the objectives well, despite the lowest damage dealt percentage." Obviously, people have these thoughts already, but this way it's far more tangible and accessible.

[Older Frame's Passives rework]

You didn't even mention Loki's terrible passive, lol.