Tobirama was a racist... there is no way around it.

The guy was involved in a war with the Uchiha clan as a child and as a young adult. Later when his brother ( a genuinely Good person and a great leader, Hashirama ) had a choice to kill the leader of the Uchiha or to make a pact with him in order to establish peace, Tobirama tried to make his brother believe he should not do that and that they should just kill this "Evil Uchiha leader". Once Konoha was built he made sure Uchiha Madara would not get in a position of power and used the "Democracy" card. He made sure he would become the second Hokage. Some years later after his brother was dead, he decided that these Uchiha's were to dangerous because of their "genes" and that they can not be trusted and therefore they deserve to be put in a ghetto and be spied on 24/7 by his secret service aka the Anbu aka The Gestapo. (Sound familiar anyone O_o ? ). He decided that Uchiha's will get a position of "Great power"... watching a prison -_- . Of course there was no Uchiha member even considered as a potential future Hokage which was proven when he decided that Sarutobi Hiruzen should be the next Hokage ( A great Ninja but also someone who later had proven to have the balls to order a genocide of an entire clan/race.) something i am sure Tobirama was aware of ( Aware of the fact that Sarutobi would have the guts to make hard decisions not aware that he will probably wipe out the Uchiha clan ). I wonder where was Tobirama's famous love for "Democracy" then. Of course one can always argue that he probably knew that he was about to get killed and that Danzo was a little to extreme but then again... aren't the people of Konoha the ones who deserve to choose their next leader??

All in all i don't personally think that this guy was truly evil or that he even had plans of getting rid of The Uchiha's for good. I think he was just a man who lost most of his family at the hands of the Uchiha's as a young man and was raised to hate and never trust an Uchiha. He probably did his best to lead the village but since he doesn't seem to be sorry that he basically made the very existence of the Uchiha's in Konoha uncomfortable to say the least... tells me that he probably had some serious issues...

Last but not least... HEIL TOBIRAMA!