I've been in several of the Patina restaurants and while they strive to be of higher quality than an Olive Garden, the Patina's feel very similar to each other. Certainly not a one of a kind experience and not particularly authentic in feel. In fact, they feel very Americanized, like many mid-level Italian restaurants in many American cities.
That's not necessarily bad, it's all about what you want.
Alfredo's did serve some of their pastas as appetizers if you wanted them that way (at least they did on our visits). Their Fettucine Alfredo was like none I have had anywhere else, including places like SF's North Beach. They are/were family owned and felt nothing like a chain.
Disney's moves in World Showcase have nothing to do with being authentic. They simply look for the best business deals they can make. That's why Alfredo's left and why Patina came in. It's also why there hasn't been a new pavilion in over 20 years.
I agree though, it's all about personal preference. Certainly some like the new restaurant better and that's fine. Neither could really be called a completely authentic Italian restaurant (the same is true of every other restaurant in WS). But Alfredo's had several edges over Patina, and if you are going on pure feel, it wins the authenticity battle hands down.
Again though, doesn't mean you will like it better.
You mention Shula's, and it is hands-down the best steak on WDW property. A couple of key differences though. Shula's is an American steakhouse, so authenticity is a non-factor, in America at least. Also, the competition on WDW is virtually non existent. Sure, places like Yachtsman and Le Cellier call themselves steakhouses, but they really aren't striving to be a true American steakhouse. But you are right, certainly being a chain does not automatically mean you are of lower quality. That said though, Shula's hits their mark much better than the Patina's, at least the ones I have been to.