I'm gonna try to summarize why the Raid Suit is important to Sanji's character.
First, he is, but he actually ISN'T a Vinsmoke. Sanji doesn't have the modified genes, like his siblings. His mother took some poison/medicine to make at least one of her children a normal human. During his life, he was seen as a failure, who, instead of being a bitch ass noble who deserves only to be beheaded, was a kind and normal kid. He got trashed for his entire life for this, and found a passion in cooking. Something that he thought was fun to do, even if he wasn't any good. His mother was happy for him. But she died and he was alone. Reiju never confronted her father or brothers, because she was afraid that she would get trashed as well.
When Sanji left, he cut all ties with the Vinsmokes, even Judge himself didn't think of Sanji as his son, only failure. Watch Game of Thrones and see how Tywin treats Tyrion.
Sanji would later find a father figure in Zeff. He would learn how to cook from him, and would also get trained by him. He got strong not because he was trained to be a perfect soldier, but because Zeff was a competent teacher and taught Sanji how to fight with his legs, so he would keep his hands only for cooking.
During WCI, Judge uses Sanji as a sacrificial lamb, not as a son, to form an alliance with Big Mom. His ties with Sanji were only convenient for him at the time, but he still refused to see Sanji as a son, only as a tool. His brothers were still the same dicks they were before.
They humilliated him, trapped him, blackmailed him, put him in a corner from where he could not escape or ask for help. Pure despair.
And YET, despite ALL THAT, he STILL TELLS LUFFY THAT HE WANTS TO SAVE THEM. NOT JUST REIJU, BUT ALL OF THEM. Why? Because his biggest trait, is what Judge thought was his biggest flaw. His kindness. He doesn't want to save them just because they are still his family. He wants to save them because it was the right thing for him to do. It he were to turn a blind eye to it, he thought his father ZEFF would scold him for it. He deeply respects ZEFF as his father. His mentor, his guide.
Then he saves the douche squad. Much to their surprise. he heartless, emotionless douche squad was simply flabbergasted that the "failure" would be their savior. So they decide to "repay"him. They later save Sanji, and decide to give him a Raid Suit, because he was still weak. But instead of trashing him for it, out of respect, they simply helped him to improve. Like a normal family should do.
But it wouldn't erase all the bad memories, so Sanji, at first, didn't want to use it. Germa science is what created the abominations that were his brothers, caused his mother's death, and was the ambition that drove Judge to trash Sanji all his life.
BUT, he was not strong enough to go for the future enemies. They would need EVERY help they could get. How could he simply ignore that boost right in front of him? So, being too soon or not, he decided to use the Raid Suit, despite EVERYTHING he went through with the Vinsmokes. He deciding to use it, because getting stronger and protecting his friends is more important to him than his grudge. His friends brought him enough hope to break his trauma. Him using the Raid Suit is the culmination of ALL OF THAT.
I REALLY struggle to understand why people can't at least recognize this fact. You don't have to like the character, you dont have to like the raid suit, but it's not a "mere power up just because". There's A LOT going on behind it.
P.S: Enma is still trash. Give back Shuusui.