Pretty much! While promoting Captain Marvel, Brie Larson didn't seem respectful for the characters that came before her. She just swoops in with her random, crappy movie JUST before the finale happens and is all like "I'm the best, and the strongest. Deal with it." Even without her feminist angle, this approach was just so off-putting for so many fans. They say that it takes years to develop a great story, and seconds to completely destroy it ... THIS is the one of the biggest reasons as to why the fans were worried and vitriolic.
As a lifelong, avid fan of Marvel Comics, I honestly wouldn't have been happy if the MCU had followed the comics too closely and did the Adam Warlock thing. Accurate to the comics? Absolutely! However, it would have been a disservice to the MCU's 11-year narrative to have what is essentially a deus ex machina to come in and save the day. It wouldn't have worked on film, plain and simple. I was very fearful that Captain Marvel was actually going to be the "Adam Warlock" of the MCU because of how powerful they made her (she ain't THAT powerful in the comics!). I breathed a huge sigh of relief when that didn't happen in the movie at all.
I'm a fan for a reason. The MCU has given me something special as a big Marvel Comics fan. If they make something I like, I'll say it. If they make something I hate, I'll say it (which I have already).