I'm in favour of the tits on a stick look, absolutely amazing. But to compliment those tits, you need to balance out the front with the back.
Take Blondie for example. the perfect tits-on-a-stick real life Barbie doll.
She looks great as she is, I love a tight butt. Hers is nice especially since she starting working out.
However I can't help but think how much hotter she would look with some butt implants!
The way I see it, a tight butt is cute and a big fake butt is hot! There is a difference between hot and cute for sure. Lilly4K, MaryMadisonLove, are all super hot women. Allegra Cole looks amazing with her fake butt, it compliments her perfectly.
But Blondie Bennett looks great as she is, because she's a cute doll, nevertheless in my opinion she would look so much better with a big fake butt. See this morph here.
It greatly depends on the body type, if she's slim and has a nice butt, butt implants are not "necessary" so to speak. But some girls have wide hips and a flat butt which would definitely 100% be improved by butt implants. See MsPalomares, Staci Doll, EssexBunny.
There are some skinny girls with tight butts that would look amazing with fake butts, like Blondie, SexyCyborg, Jessica Weaver, etc.
It makes their body more feminine and butts are nice to grab, especially when there is a big silicone implant inside lol!