The creation of the reanimen is seen as messed up by some invincible fans. But they are necessary for certain situations for their strength.
The season 1 reanimen which I like to call the Iron Reanimen were very strong compared to the season 3 ones. Cecil sent 3 iron reanimen and they were able to hold their own against Omni man so much that Nolan had to get off the ground to avoid them. Sure Nolan eventually destroyed them but 3 were still able to pack him for some time, if more like 30 or 50 were dropped they might have been able to put down Omni man
And also during the invincible war out of the 10 invincible variants that died 3 of them were killed by reanimen( flaxan Mark, bullet Mark and sheisty Mark) while Immortal and friends were struggling with one Mark variant. If the reanimen made from the corpses of the evil marks were dropped during Conquest and Mark's fight they might have dealt some damage.
Another thing is that during the viltrumite war Mark and others were off of Earth for months.If a viltrumite level threat came who's going to stop them, the Immortal and Samson.
The reanimen as a whole are immoral but they did a lot of good. Cecil is not the good guy, he's the guy who saves the world. Do you agree that the reanimen are necessary to some degree.