Read the manga again. Theres a reason why the beasts are "beasty" you can hear kurama and shikaku talk about how the humans just cause wars and that they hunt power and control it but they find themselves fail.
This means that they go after the tailed beasts, who lets say are peacful at the time, and try to capture them and turn them into weapons. They defend themselves and defeat those humans. Now that theyve harmed the humans, though they had the intent of capturing the beasts, the beasts are considered terrorists and must be taken care of. Now, not only you have people who want to use the beast, you also got people who are trying to kill or capture the beasts because they are considered bad.
This is why kurama embodies rage and pure evil. Its probably because he protected all the beasts and that he is enraged on how the humans mistreat them and had the audacity to dubbed them bad.
The bijuus are just misunderstood creatures.