I don’t agree. Jaimie showed that he’s a nuanced person throughout the show. Individually, he was a good guy if not (early on) vain and arrogant. But his love for Cersei overwhelmed everything. He wouldn’t have pushed Bran if it wasn’t for her. He wouldn’t have murdered his cousin if he didn’t want to get back to her. etc. He basically said as much after Cersei spurned himfollowing his escape from Robb.
There were spaces where Cersei didn’t pervade and Jaimie was able to rebuild his humanity. His relationship with Brienne was one such space. Cersei was aware that something had gone on between Brienne and Jaimie, but it was all too easy for her to put her claws back in. Jaime armored and armed Brienne, but sent her off, albeit with some regret. Perhaps that regret came from his doubt as to whether he could ever become the person Brienne saw in him so long as he was with Cersei. I think that's why he gave a relationship with Brienne a try during and after the Battle of Winterfell. Unfortunately for him, he realized that he didn't make a mistake by choosing Cersei before, and once again set off on a quest across the kingdom to find her again. I believe Brienne and Cersei offered two visions to Jaimie of the life he could lead and the person he could be. While he wanted the life Brienne could offer, he didn’t have the strength to say no to Cersei. IMO that's why he found himself “hateful.” I also think that's why Brienne phrased her words during their final parting the way she did.
Really, only Tyrion could motivate Jaimie to rebel against Cersei to any degree. Tywin, the most formidable man in the kingdom, direct Jaimie to do much, but his love for Cersei was always powerful enough to drive him to near- suicidal lengths. A few words from her had him sailing off to Dorne, a place Bronn said was populated by people who were only interested in "fighting and f*cking." Cersei took his devotion and borderline naivete for stupidity, and exploited it. Maybe she was partially right, but I'm not 100% convinced.
I think Jaimie struggled throughout the show to prove to himself that he could be a good person, but in the end, he accepted his limitations and chose her. Like the writers said, he may not have been happy about it, but it was a fact about him. George RR Martin has repeatedly said that the true battle between good and evil isn't a struggle between two diametrically-opposed political forces, but the struggle in the human heart. To that end, I found Jaimie to be one of the most interesting characters in the show. He violated the trope of the redeemed man, but had his own sort of appeal anyway.
I found his and Cersei’s death to be very poignant. Cersei was an evil person without a doubt, and I think the show stopped delving into her character--possibly because the writers wanted her to be a spectral presence, or possibly because the death of her children had killed off whatever humanity she had left--but I still felt something when she lost her composure and said that she wanted to live for her unborn child’s sake.