Yeah, that was the main problem with 2.0 in general. They knew how they wanted the characters to end up, but had no idea how to actually bring them - in a natural and believable manner - from point A to point B. Their growth was incredibly rushed and artificial, partially due to the lack of screen time, which was instead wasted on needlessly long and frequent action sequences. Great priorities, right? So much for Evangelion being a psychological anime.
Characters particularly guilty of moving from point A to point B without the necessary development behind it were Shinji and Asuka. And given they were, alongside Rei, the main characters, it goes to show how poor the handling of the characters was in general. The plausibility of Shinji's little spiritual breakdown after the incident with Asuka heavily relied on his connection to her, yet their bond was so flimsy and underdeveloped, that the developments carried nowhere near the necessary emotional weight behind them. It all felt very contrived. It was like Anno and company went...
"Guys, we need Shinji to hit rock bottom by the end of the movie."
"Huh. How can we get him to break like that?"
"Oh, I know! Have Asuka get mangled up!"
"But… they've just met."
"So? You think modern audiences care about that?"
"Well, we should at least give them more character bonding scenes then…"
"Nah, we can't afford to waste time on those. Tell you what, just give Asuka a new ludicrously fanservicey plugsuit. That ought to make up for everything!"
So yeah. And Asuka was already pretty bad in of herself. Again they had an idea of where they wanted to take her, but instead of properly developing her character towards the desired result at a steady and believable pace, they basically skipped her character arc entirely (because otherwise those lovely action scenes might be compromised!) and shoehorned in a completely unwarranted character epiphany at the last second. When she was telling Misato she was going to be fine now I felt absolutely nothing at all, because there were no scenes whatsoever that even built up to such a change. I felt so cheated. In the original series, Asuka fought her heart out for to attain happiness and overcome her pathological issues, but still met a tragic end, yet here she does basically nothing the entire time, but still manages to somehow find this completely artificial happiness and catharsis by the end (just before becoming a plot device to fuel Shinji's depression). Really, Anno? Is that your idea of pleasing Asuka fans and fans of, you know, what made Evangelion Evangelion?
So yeah, I don't mind suspending my disbelief a little when it comes to physical feats in action sequences and whatnot, but when it comes to character building it's another story. Evangelion is a character study at heart and therefore the verisimilitude of its characters is a crucial factor in its general worth and relevance to humanity. But, as you said, Rebuild took the viewers' suspension of disbelief for granted way too much. And yet… it still managed to be ridiculously successful and well received. That's the saddest part, the audiences are essentially proving Anno right in that he doesn't need to go to great lengths to skillfully portray believable and complex characters anymore, since lavish action scenes and "service, service!" will do the job. Is it a coincidence that action and fanservice were the only purposes Mari's character served? She perfectly embodies everything that is wrong with Rebuild and the anime industry today. And to see Anno, who rebelled against the conventions of the mecha genre back in the day, completely conform to that same sorry state of the industry is just really disappointing to me. That's why I can't avoid lashing out at Rebuilding like this when I get the chance. Terrible experiences like that deserve to be hurt back, you know?