Anyone who has seen the S and Stars seasons of BSSM know about the Outer Senshi. Particularly the main two, Uranus and Neptune. In the S season their mission was to find the three tailsmans and the messiah. They will willing to sacrifice anyone or anything for the mission. They even made a pact not to save the other so one could continue the mission. They were also willing to kill the Messiah of Silence, Sailorsaturn, to prevent the Silence, even though they knew Tomoe Hotaru lived in her.

In the Stars season, the Outer Senshi fight against Galaxia. They are losing and Galaxia offers them her bracelets, which will make them her slaves. Saturn and Pluto refuse but Uranus and Neptune accept. They kill Pluto and Saturn and attack Eternal Sailormoon and the Starlights before using their bracelets to attack Galaxia

The reason Uranus and Neptune do this things is because of their devotion to the mission. When their plan against Galaxia fails she takes their bracelets, killing them. Sailormoon asks them why they did it and they reply "This is our way." But do they take their desire to fufill the mission to seriously? Maybe. Maybe not.

Since the beginning it has been shown that the Outer Senshi are different from the Inners. The Outers guardred the Silver Millennium in the past. They probably led lonely, solitary lives. The mission was their focus, the thing that kept them going. We know nothing about the childhoods/upbringins of Uranus and Neptune. This might have an affect on the way they fight. And also I think a strong desire to protect their princess, Serenity, is another reason why they act the way they do

So in conclusion, people love to criticize the actions of Uranus and Neptune. But really think about it before you form an opinion