And, though I'm not pro-Uchiha anything, I can understand why they would have been pissed that the only guy from an apparently dead clan (Namikaze) gets the Kage role, while this huge clan of powerful shinobis gets passed over.
In the case of it with the Uchiha, Tricksie, I blame some of that on Tobirama's prejudice against them since he carried on the bitterness of his father and passed it on from all the fighting with the Uchiha, while Hashirama wanted legitimate peace for them, even when Madara snapped and wanted to fight him when the Uchiha chose to side with Hashirama as the first Hokage, while he was willing to let Madara do it before he accepted his role. And that prejudice kept spreading into some others, like Homaru and Koharu, Hiruzen's comrades before he became the third Hokage. And we saw Hiruzen tried to have some peace with the Uchiha, but the bitterness they felt at the prejudice is what led Sasuke and Itachi's dad, Fugaku, to attempt a coup, being willing to use his sons as spears against the Leaf, and how Danzo was no different, sicne not only did he not believe in the Uchiha really, but he coveted their Sharingan for himself, like how one of the Ultimate Ninja Storm games showed he stole Hisui's Sharingan before he could attempt to use Kotoamatsukami to stop the coup.