Firstly, I'm pretty sure that you were the one who started with the rockstar comparisons. Secondly, yes, GTA does have a lot of scripted missions. As does watch dogs/AC etc. GTA also does give you a lot of freedom at times, which I guess could also be said about UBI games. And yes, you made some good points about the world building comments, but like a lot of things in ubisoft games, it often feels half baked. See the aforementioned ambulance, the repetitive encounters, the fake reflections in the windows etc.
And yes, you're allowed to gripe about GTA, but the world rockstar created feels far more real and lived in than any ubisoft world. I also find your complaints about the movement a little rich when, over the course of at least six mainline creed entries, knee high obstacles were an issue for your badass parkouring assassin. Oh, and the lack of any real stealth system until the 7th entry in a series where you are meant to be an assassin is really pitiful.
No game is perfect. Truth be told, I've become pretty disenchanted with the aaa game industry as a whole, but assassin's creed really sticks out like a sore thumb for me. I love the idea behind it and I want to love it, but after too many entries, little change and so much wasted potential, I'm done. Over the course of the 7th generation, I gave ubisoft close to $500 of my own money for a series of games with declining quality, and I'm sick of it. You want me to play unity so badly? Send me a copy. That's the only way I'll play it. After years of frustration with dwindling quality and wasted potential, I've decided to vote with my wallet. Ain't giving them a penny until they actually try hard and earn it.
I'll close out my post by saying that I think you and a small group of others on gaf misunderstand people who feel like I do. We're not hating on ubisoft for no reason. We believe in the potential this series has, but we're not seeing any real attempts by ubisoft to realize that potential.